Mohs Scale: Gemstone Durability & Hardness 

 

 

 

Information About Gem Spieces 

Alexandrite            

Alexandrite is quite simply an exceptional gemstone. Associated with Russian Tsars and nobility many regard this amazing stone as being in a class of its own. First discovered in the early nineteenth century near the Tokovaya River in the Urals, Russia, Alexandrite was named after the Russian Tsar Alexander II. Alexandrite became the national gemstone of Russia; its beautiful colour change from green to red signified the Russian Imperial colours. People the world over are still amazed by the beautiful colours produced by this gemstone. The ideal colour change is likened to the colours of traffic lights, from bright green to a rich red. The reality is that the best Alexandrite for sale now is more of a bluish-green to a purplish-red.
Alexandrite will appear green in natural daylight and will turn to a beautiful red in incandescent light. Another major factor in determining the quality of Alexandrite is the percentage of the colour change, with a 100% colour change being the pinnacle. The lower the percentage, the lower grade, hence lower the price. However, due to the rarity of Alexandrite even for a stone with a relatively small percentage of colour change these mesmerizing stones can still command a hefty price tag. If the origin of a stone is proven to be that of Russian heritage then you really are in possession of a rare gem. When it comes to the clarity of Alexandrite many you see will have negative crystals and rutile inclusions. As long as these inclusions are minimal gemologists tend to think that they actually add beauty and originality of the stone.  Many of the finest pieces nowadays will not come up for sale on the open market with their owners content to keep them safely tucked away where they can admire them at will. Alexandrite is a member of the Chrysoberyl family but unlike other Chrysoberyls it contains titanium, iron and chromium and it is the chromium that creates the fantastic change in colour.
There was a real lull in the finding of good quality Alexandrite until in 1987 they were discovered in Hematita, Minas Gerais, Brazil. Displaying a good colour, colour change and clarity this was a very refreshing find. More recently Alexandrite has also been found in parts of Africa with the best stones said to come from Tunduru, Tanzania. This magnificent gem has another fine quality, it has a hardness of 8 ½ on the Mohs Scale which means it is suitable for setting in all types of jewellery. A real connoisseur's gem no picture can do this stunning stone true justice.

 

 

Amethyst                

Amethyst is a one of nature’s real stunning accomplishments. Its magnificent purple colour is totally mesmerizing. Purple has always been associated with royalty and nobility, there are some stunning examples of Amethyst amongst the British Crown Jewels. Even in Egyptian times this beautiful stone was said to be a favorite with royalty. Amethyst is believed to have many mystical powers. Translated from Greek, the word “amethystos” means not drunken. Legend says that if you were to drink from a goblet made from Amethyst you would remain sober. Tibetan people believe that the gem is sacred to Buddha and often wear Rosary beads made from Amethyst.
Amethyst is the most valuable member of the transparent silica mineral quartz. The most sought after colour is a beautiful deep purple with slight red undertones. If heated, this stone will turn yellow which occurs when Citrine is produced and gets its colour from. Amethyst is mined the world over from Brazil, Argentina and Bolivia to India, Sri Lanka and some African countries. It is generally noted that the South American variety tend to be larger in size but the smaller stones found in African countries have a more saturated colour. Sometimes found in a lighter shade of purple it has been given the name “Rose de France”. Amethyst is a particular favorite with designers due to its varying shades of outstanding colour, affordable price and association with royalty.

Amethyst (Quartz) has been graded as 7 for hardness on the Mohs Scale thus making it suitable for prolonged wear in any setting or type of jewellery. Its regal colour is sure to continue to be very popular amongst everyone for many years to come and with its affordable prices it is certainly a gem that is not out of reach for the buying public.

 

 

Aquamarine          

Aquamarine is a beautiful gemstone that belongs to the Beryl family which also boasts the splendor of the Emerald. The name Aquamarine derives from the Latin words aqua, which means water, and mare, which translates to sea. As the name of this stone may suggest the colours range from an enchanting sea blue to blue with hints of green or teal. The colours are produced by traces of iron found in the stone. It is generally recognized that the stronger the shade of blue in the stone the more desirable and expensive this gem becomes. Aquamarine is sometimes subjected to a heat treatment to disregard any yellow in the stone, this treatment also enhances the shimmering shades of blue in the stone.
Aquamarine is found in a number of countries but Brazil is where the best pieces have been found, notably in the Santa Maria de Itabira mine. Brazil also boasts the paler aquamarine called Espirito Santo. Mozambique in Africa has also produced some exceptional stones, likened to the Santa Maria gems in colour, they have adopted the name “Santa Maria Africana” so as not to be confused with their Brazilian counterparts. Various other places in Africa, the U.S.A, Pakistan and Afghanistan also produce this stunning gem. Aquamarine is usually free of inclusions which is why it has such a brilliant luster, also it can be found in fairly large sizes. It has become a favorite with designers for these very reasons.
Aquamarine is a hard wearing stone which has been graded 7½ - 8 on the Mohs Scale which measures the hardness of gemstones. For this reason Aquamarine has been cut into extravagant and beautiful shapes. They are gemstones that can withstand continual wear, suitable for every occasion. A definite favorite with women across the world, its beautiful colours elegantly compliment any skin tones.

 

 

 

Peridot                     

Peridot is a truly beautiful gemstone. When found in good examples, their green colours are quite magnificent. It is sometimes referred to as the “Evening Emerald”. It is by no means a new find; it can be dated back as far as Egyptian times when it was discovered on an island called St. Johns (now known as Zeberget) off the Egyptian coast in the Red Sea. Cleopatra had a vast collection of amazing jewellery and what were initially thought to be Emeralds were in fact Peridots. Folklore says that Peridot brings peace and good luck to whomever possess or wears it. Also it is said to help with many physical disorders by bringing vitality and healing to the body.
Peridot is a transparent specimen of the mineral Olivine and is also sometimes called Chrysolite when Golden Yellow in colour. Its colour comes from iron content in its crystallized form. Depending on the amount of iron its colour can range from a beautiful lime green to a yellowy-green to a duller brown. The lime green examples are the most attractive and sought after pieces. Peridot is mined the world over in places such as Egypt, Minas Gerais in Brazil, a variety of places in America, Myanmar, China and Pakistan. In the 1990’s a new deposit of Peridot was discovered in the Suppatt region of Pakistan with an outstanding colour not seen before, this made for an instant revival in the popularity of the gem, hence the rise in value of fine examples found on today’s market. Fairly large with good colour and clarity, Pakistani Peridot is indeed a rare find and would command a hefty price tag. Some pieces can be quite heavily included but there is also a good amount of clean Peridot being mined. As a general rule this gem will not have been subjected to any kind of enhancements therefore totally natural.
Peridot has been graded as having a hardness of 6.5 – 7 on the Mohs Scale. It is suitable for all types of jewellery but a little extra care is suggested when worn on a regular basis. The appearance of this beautiful gem does not change in any lighting conditions whether it is natural or artificial light. This makes it a firm favorite for evening wear and would accompany the wearer elegantly to any function.

 

 

 

Ruby                          

Rubies are one of nature’s finest accomplishments. Known as the King of Gemstones, Rubies are recognizable to many for their magnificent red colour. Ruby comes from the red variety of the mineral Corundum. Corundum is one of the hardest minerals on earth, measuring 9 for hardness on the Mohs Scale. Rubies come only second to Diamonds. Pure Corundum is totally colourless, with certain other minerals such as chrome, titanium and iron creating the colour. Sapphires also come from the mineral corundum but only when red can it be called a Ruby; any other colour conundrum becomes known as Sapphire.
Rubies come in varied shades ranging from pink to a deep red which are noticeably more desirable than the lighter Rubies in today’s market. Mogok in Burma (now known as Myanmar) produces what are regarded by many as the best colour available. They display a stunning and vivid red which, in the finest examples, will sparkle in any light, whether it is natural daylight or artificial light. There are many places around the world that also produce sought-after Rubies. Those mined here in Thailand are a slightly darker red if compared to the Mogok Ruby while the Ceylon Ruby is an altogether different shade of red, tending to be a lighter colour. Many of the Rubies for sale in today’s market have been subject to what is known as “high temperature heat treatment”. Such treatments enhance the colour and (or) clarity of the stone. Stones mined prior to1970 are an exception as they were not enhanced in this manner.
To find a good colour, 2 carat plus sized Ruby with minimal inclusions today is very rare indeed. To find a good quality piece that has not been heat treated is even rarer. The prices of such stones reflect their rarity with astronomical prices being paid for a top graded Ruby. Smaller good quality stones are becoming just as rare from year to year as many collectors will buy them and simply add them to their collections. The price of this awesome gemstone is not necessarily diminished if they show slight inclusions that do not affect the brilliance of the stone. Many people actually think that small inclusions can add to the charm and originality of the stone. As we have touched on before, Rubies are extremely hard gems which make them ideal for everyday wear and can be set very easily in all types of jewellery.

 

 

 

Sapphire                  

Sapphires are one of nature’s true wonders. They are renowned for their beautiful colours, blue being the most sought-after. The first discovery of these magnificent gems was said to be in Ceylon (Sri Lanka) stemming back to ancient times. They are made from the mineral specimen Corundum which also produce Rubies. Corundum is made up of certain minerals, aluminum oxide which centuries ago formed into splendid crystals, however other elements, such as chrome and iron, give Sapphires their truly outstanding colour.
Peoples tastes vary widely but experts tend to agree that the Kashmir blue stones are the pinnacle of all Sapphires. They are a splendid deep velvety blue in colour with a beautiful sheen to them. Kashmir stones were first discovered as little as two centuries ago. There has been very little excavating from the Kashmir mines since the 1930’s which makes them all the more prized. Burma has also produced some of the finest Sapphires. Other stunning shades of blue are the lighter Ceylon (Sri Lanka) Sapphires which are known to have a fantastic brilliance in any light source. Pinkish - Orange Sapphires have recently become very popular due to their wonderful colour. They have been named Padparadsha, which translates to Lotus Flower, and these truly stunning stones can display the colours of the most charming sunsets. There are also some fine examples of Yellow, Purple, Green and Pink sapphires.
A large quantity of Sapphires sold today have been subject to “high temperature heat treatment”. Such treatments enhance the colour and (or) the clarity of the stone. Stones mined prior to1970 are an exception as they were not enhanced in this manner. Keep in mind that to purchase a natural Sapphire of good quality with a size of 1 carat plus can be a very expensive experience. These days most of the larger un-heated stones are safely locked away in a connoisseur’s collection. Sapphires are graded 9 on the Mohs Scale, diamonds being the only other gemstone with a higher grading.

 

 

 

Spessartite Garnet

Spessartite is a beautiful and charming stone and is a member of the varied and extremely colourful Garnet family. In a very remote part of Namibia, Africa, hardly touched by civilization the first Spessartites were discovered in 1991. The Kunene River meanders its way through the Namibian – Angolan border where these exceptionally brilliant gems were first found. Spessartite is, in fact, a variation of the extremely rare Spessartine gemstone, also a member of the Garnet family.
Realising the natural beauty of this find, the mines in Namibia near to the Kunene River were exhausted fairly quickly. Stones found near the surface were soon scarce so mines were excavated deeper but even these mines were so soon depleted of this fantastic find.
There were various names chosen for the find but eventually the name Mandarin Garnet stuck due to its beautiful orange colour. Three years later in 1994 more orange stones were discovered in the North-West of Nigeria; these once again turned out to be Mandarin Garnets, so although big sized clean stones are rare and can command a serious price, there are a good selection of smaller (1 carat plus) on the market today.
Spessartite Garnet is a wonderful gem for a number of reasons. Firstly, its dazzling colour is easily recognizable. The colour can range from the most desirable tangerine orange to a rich Mandarin colour and then to a deep fiery red. Some also describe the best colour Spessartites as Fanta orange.  As is the case in all of the Garnet family, it has a high light refraction index which leaves people in awe of  this gem’s outstanding luster and brilliance, even in bad lighting. For pieces that are free of inclusions, the Mandarin Spessartite Garnet will still gleam and sparkle. With a hardness of 7 ½ on the Mohs scale, this stone is suitable for every occasion and for everyday wear. It is not known how much more of this gem there is to be found in the earth and therefore the price of sizes 2 carat and larger, with good colour and little to no inclusions, are becoming very expensive in today’s market.

 

 

 

Spinel                        

Spinels come in many splendid colours; in many people’s eyes, the red Spinel stands out above the rest. Known as the great imposter of gemstones, the red Spinel has been mistaken for ruby on several occasions. The British crown jewels harbor a magnificent Spinel of incredible size which was thought to be a ruby due to its remarkable similarities in colour and mineral contents. The famous “Black Princes Ruby” is in fact a truly amazing red Spinel. Weighing an unbelievable 170 carats, it sits proudly in the Queens state crown. This Spinel is absolutely priceless given its history, awesome colour and clarity.
The name Spinel derives from the Latin word “spina” which means thorn as this gem has sharp octahedral crystals. Spinels and rubies are particularly similar in their chemical make-up. Both have aluminum oxide content while the Spinel also contains magnesium. Also, both of these fine gems have the element chromium in them, producing such splendid colours. By no means is the Spinel limited to just one colour. The rare blue Spinel has adopted the name “cobalt blue”. The best cobalt blue Spinal can be found in Sri Lanka. The sumptuous pink variety can be found in Burma (Myanmar). Also on today’s market, beautiful purple/violet, orange (known as flame) and other paler or richer varieties of the above mentioned Spinels can be found.
With a hardness of 8 on the Mohs Scale, it is definitely suitable for prolonged wear in any type of jewellery.

 

 

 

Tanzanite                

Tanzanite is a real connoisseur’s gemstone. This remarkable gem is only to be found in one part of the world, Merelani, Tanzania, East Africa. Discovered only fairly recently in 1967 by Massai natives, this magnificent stone instantly made an impression. People viewing it for the first time said that it literally took their breath away. The mines in Merelani were constantly under close scrutiny by guards armed with rifles. It has been suggested that some of the miners swallowed large pieces of rough form Tanzanite due to the meager wages they were earning. The much talked about “D Block” mine is said to have produced the finest quality pieces. Tanzanite is in fact blue Zoisite but it was re-named after the world famous jewelers Tiffany and Co. decided that a more appropriate name would be Tanzanite due to the fact that it was discovered in Tanzania.
Tanzanite colour when at its best is a superb deep blue with a purple hue around it. A lot of Tanzanite is heat treated to a temperature of around 500 degrees Celsius to enhance its colour. People sometimes confuse Iolite with Tanzanite due to their very similar colours. Both stones have a high concentration of pleochroism which causes the stone to show three different colours when rotated. But ultimately Iolite comes in second; its colour cannot compare to that of the elegant Tanzanite. With its brilliant luster, this stone can attract very large sums of money in today’s market; large stones can be well in excess of $1000 per carat. These beautiful gems are usually quite clean and free of inclusions.
Tanzanite is a fairly brittle stone and should always be handled with the utmost care. It has a hardness of 6.5 – 7 on the Mohs scale, therefore it’s not wise to wear it in everyday jewellery. Tanzanite is a gem to be savored and worn on those special occasions.

 

 

Topaz                        

Topaz is an extremely beautiful gem. It has always been associated with legends for centuries. The Romans associated Topaz with the mighty “Jupiter”, the God of the sun. Egyptians believed that the golden glow of Topaz was given by their god of sun “Ra”. The name Topaz is derived from the Indian Sanskrit word tapas, which translates to fire. This magnificent stone is found the world over, from America and Brazil to many Asian and African countries. It can also be found in the Scottish highlands, namely the Cairngorm Mountains, which over the years have produced some fine specimens.
Topaz comes in many different colours, from stunning London blue, yellow, pink and sherry red, which is mined in Brazil and Sri Lanka. You can also find an orangey/red Imperial Topaz that is very rare. Even rarer still are natural blue stones; generally the blue variety has been irradiated and heated from colourless crystals. Topaz is an aluminum fluorite silicate containing fluorine. It is one of only a handful of gemstones that can grow into huge crystal formations if the conditions are favorable. Topaz is the hardest silicate mineral on earth and is also one of the hardest minerals in nature. Given its impressive durability and large sizes it has always been a favorite with many jewelers and collectors. It has a brilliance that can be truly dazzling due to the fact that most Topaz should be relatively free from inclusions.
Topaz has been graded as 8 on the Mohs Scale. Although a hardy stone, when storing Topaz you should take care to make sure that it is stored separately as the facets can be a little brittle when they come into contact with other jewellery.

 

 

 

Tourmaline             

When the word Tourmaline is mentioned, it instantly reminds many people of all the magnificent colours of the rainbow. These gorgeous gemstones are formed from a mixture of aluminum-borosilicate crystals. They are something of a miracle in the gemstone world with their hugely varied colours. It is said that no two pieces are alike due to the fact that they change colours in different lighting and surroundings. Tourmaline is the national gemstone of America but is mined the world over today, with pieces being excavated from Brazil, Africa and Asia.
There are several names for specific colours of Tourmaline. These range from, surely the most renowned, Paraiba Tourmaline, so named because it was discovered in the state of Paraiba, Brazil. It has an
astonishing neon blue to green colour. Then there is the Rubellite, a name given due to its likeness to the red Ruby. There are bi-colour Tourmalines which, as the name suggests, are two colours; and even rarer are tri-colour Tourmalines. Another rare colour is a blue variety known as Indicolite. The list is endless! The price of this radiant gem ranges nearly as much as the colour. True Paraiba stones can command as much as $15,000 - $20,000 per carat. Very rarely will you see these unique stones for sale, they are mainly in the hands of collectors who are understandably reluctant to part with them.
Tourmaline is a fairly hardy stone; it measures 7 on the Mohs Scale making it suitable for everyday wear. You will almost certainly find a colour to suit every occasion or mood you happen to be in.

 

 

 

Tsavorite Garnet 

Green Tsavorite Garnet is one of the gem world’s most beautiful stones. Gemologist Campbell R. Bridges was prospecting in the North Eastern part of Tanzania in the late sixties when he discovered large, oddly shaped stones. Inside these stones were stunningly beautiful green crystals which, after testing, turned out to be the very rare green grossularite, a member of the Garnet family. Bridges hit a brick wall when he could not get an export license to take these beautiful gems out of Tanzania. Undeterred he broadened his search until in 1971 he once again discovered this shimmering green gem in Kenya. The stone was not well known to the general public. So, in 1974 Tiffany & Co. began a promotional effort in the U.S.A to make the buying public more aware of Bridge’s find. In no time other countries followed suit and before long Tsavorite was known worldwide.
Tsavorite’s name is derived from the Tsavo National Park in Kenya where it was discovered. Henry Platt, the president of Tiffany’s at the time, chose the name. Tsavorite is so desirable because of its incredible colour. It ranges from a refreshing pale green to a beautiful bluish green to a stunning deep forest green. The superb luster and fire to Tsavorite is due to the particularly high light refraction index, as is the case with all Garnets.
Unlike many gems in today’s market, Tsavorite is not treated to enhance its beauty. Quite simply, it does not need enhancing as it is naturally wonderful to look at. With a 7 ½ on the Mohs Scale, it is suitable to wear on a fairly regular basis. In today’s market, Tsavorite is commanding a very high price due to above mentioned factors. To find a 5 carat plus stone would be extremely rare indeed, with smaller pieces ranging from 1 carat plus fetching a considerable amount of money.

 

 

 

Zircon                       

Zircon is an amazing gemstone with a stunning brilliance due to its high refractive index; people have likened its luster to that of Diamonds. Mined predominately in Asia, this stone was thought to bring prosperity and wisdom to whoever adorned it. In Hindu mythology, Zircon was said to be on every leaf of the Kalpa Tree, a symbolic offering to the gods to bring good fortune. Not to be confused with cheap imitations such as its familiar namesake Cubic Zirconia, this stone can display awe inspiring colour.
Cambodian Zircons are some of the most treasured, with their beautiful neon blue colour. When pure, Zircons can be colourless and are, at times, substituted for diamonds. When inspected further, however, they are easily distinguishable from Diamonds because they are double refractive. Many Zircons are mined from the earth brownish in colour and receive heat treatment which transforms them to a stunning blue colour. Note that not all Zircons are heat treated; some are natural in colour. Blue Zircons are generally regarded as the most desirable on the market today but they also come in a variety of other colours such as yellow, red, orange, green and brown. Prices for good quality Zircon can range from $200 - $400 per carat depending on the colour and clarity of the stone.
This beautiful gem is becoming ever increasingly popular. Prices are steadily rising and mines are becoming depleted of stones. Zircons have a hardness of 7 ½ on the Mohs Scale. They set superbly in any type of jewellery, especially a ring or pendant, and are sure to stand out in a crowd with their mesmerizing colours and fire.
 
 
 
Thank you for taking the time to read our detailed descriptions, we hope they have been informative and helpful for you.