Gemstones

 

Alexandrite
Alexandrite is the rare, phenomenal, color-change variety of the chrysoberyl mineral. Alexandrite can only form when aluminum and beryllium combine with trace elements like iron, titanium, and chromium, which causes color change and is very rarely found in nature. The unlikelihood of the rare element chromium being in the right place to combine with aluminum and beryllium under exactly the right conditions to create alexandrite is what makes it so rare and valuable. At 8.5 on the Mohs' hardness scale, alexandrite is hard, tough , and durable for daily wear. Alexandrite is green or bluish-green in daylight, changing to raspberry red or purplish-red in incandescent light. Alexandrite can also exhibit the phenomenon of chatoyance or the "cat's-eye effect" when cut en cabochon. Alexandrite can be an alternative birthstone for June. It was originally discovered in the Ural Mountains of Russia in the 1830's.

 

Amethyst
    Amethyst is a violet variety of quartz and owes its violet color to irradiation, iron impurities, and the presence of trace elements. The hardness is 7 on the Mohs scale. Amethyst occurs in primary hues from light pinkish violet to deep purple. The best varieties of amethysts can be found in Siberia, Sri Lanka, Brazil, and the far East. The ideal grade is called "Deep Siberian" and has a primary purple hue of around 75-80%, with 15-20% blue and red secondary hues. The Greek word "amethystos" may be translated as "not drunken". Amethyst was considered to be a strong antidote against drunkenness and some wine goblets were carved from it. Amethyst is the birthstone of February.

 

Aquamarine
Aquamarine, the March birthstone, is a blue or turquoise variety of beryl with a hardness of 7.5-8 on the mohs scale.  The term aquamarine is derived from the Latin aqua marina or "water of the sea". It can be found in the US in Colorado and Wyoming. There are mines in Brazil, Columbia, Zambia, Madagascar, Malawi, Tanzania and Kenya. The largest aquamarine of gemstone quality ever mined was found in Marambaia, Minas Gerais, Brazil in 1910 and weighed over 110kg.

 

Citrine
Citrine is a medium deep shade of golden yellow - orange quartz and has a hardness of 7. Some citrine is colored by aluminum based and irradiation induced color centers related to those found in smoky quartz. It is found in Brazil and is the birthstone of November.

 

Diamond

Diamond is the hardest mineral on earth commanding a 10 on the Mohs hardness scale. It has an extremely high refractive index creating that dispersion or rainbow effect known to diamonds. They are one of the best-known and most sought-after gemstones. The hardness of diamond and its high dispersion of light gives diamond its characteristic "fire" making it an ideal gemstone for jewelry, especially wedding jewelry.

Diamonds are graded based on the "four Cs"; color, cut, clarity, and carat. Other characteristics, such as presence of lack of florescence, also affect the desirability and value of a diamond.

 

Emerald
Emerald is a variety of the mineral beryl colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5-8 on the Mohs scale. Other beryls include aquamarine, heliodor, morganite, and colorless goshenite. Most emeralds are highly included, so their toughness (resistance to breakage) is generally poor. Emeralds are frequently oiled in order to fill in surface reaching cracks which improves their clarity and stability. In grading emeralds, crystal is considered a close second to color. A fine emerald must possess a pure verdant green hue, and a high degree of transparency to be considered a top gem. Fine emeralds must be medium to dark, or 75% in tone. The hue should be bright green. Colombia is the world's largest producer of emeralds, Zambia being the second biggest producer. But emeralds are found all over the world including several states in the US.  Emerald is the birthstone for May.

 

Garnets
Garnets are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. All species of garnets poseiss similar physical properties and crystal forms, but differ in chemical composition. The different species are pyrope, almandine, spessartine, grossular (hessonite or tsavorite), uvarovite and andradite. Colors range from red, orange, yellow, green, purple, brown, blue, black, pink and colorless. Garnet has a hardness of 6.5-7 and is found in Madagascar, in parts of the US, Russia, Kenya, Tanzania, and Turkey. It is the birthstone of January.

 

Heliodor / Golden Beryl
Heliodor is the golden yellow variety of the mineral beryl, colored by iron. It was discovered in Namibia in 1910. The name heliodor is Greek meaning "gift from the sun." Heliodor is found in Minas Gerais and Goias, Brazil; the Ukraine in Russia; and also in Connecticut and Maine. It has a hexagonal crystal system and a hardness of 7.5-8.

 

Morganite
Morganite, also known as Pink beryl, is a rare light pink to rose colored gem quality variety of beryl. Morganite was first discovered on an island on the coast of Madagascar in 1910. In 1989, one of the largest gem morganite specimens ever uncovered was found at the Bennett Quarry in Buckfield, Maine, and was later named "The Rose of Maine". Morganite is 7.5-8 on the mohs hardness scale.

 

Opal
Opal contains up to 20% water trapped in its silica structure. Because opal has the colors of other gems, the Romans thought it was the most precious and powerful of all. When Australia's mines began to produce opals commercially in the 1890's, it quickly became the world's primary source for this October birthstone. Five of the main types of opals are; White or Light opal, Black opal, Fire opal, Boulder opal, and Chrystal opal. Play of color occurs in precious opal because it's made up of sub-microscopic spheres stacked in a grid-like pattern. As the lightwaves travel between the spheres, the waves diffract, or bend. As they bend, they break up into the colors of the rainbow, called spectral colors, resulting in play-of-color. Opal can range from 5-6.5 on the Mohs hardness scale.

 

Pearls
A pearl is a hard object produced within the soft tissue (mantle) of a living shelled mollusc. A pearl is made up of concentric layers of calcium carbonate deposited in minute crystalline form. The ideal pearl is perfectly round and smooth, but many other shapes of pearls (baroque) occur. Cultured or farmed pearls from pearl oysters and freshwater mussels make up the majority of what is sold today. Gem quality pearls are almost always nacreous and iridescent, as is the interior of the shell that produces them. Pearl is 2.5-4.5 on the Mohs scale and is considered the birthstone of June.

 

Peridot
Peridot is gem-quality olivine, a silicate mineral. It is one of the few gemstones that occur in only one color, an olive green. The intensity and tint of the green depends on how much iron is contained in the crystal structure, so the color can vary from yellow to olive to brownish green. The most valued color is a dark olive green. Peridot has a hardness of 6.5-7 and is the birthstone for August.

 

Rubellite
The name "rubellite" comes from the Latin 'rubellus', which means reddish. Rubellites are not merely red or shocking pink tourmalines. The important criteria is the way its color behaves in daylight and artificial light. A true rubellite will not change color depending on the light source. Most red or pink tourmalines display a visible tinge of brown in artificial light. Rubellites are mainly found in Brazil, Madagascar, Mozambique, Nigeria and Pakistan and some beautiful shocking pink rubellites come from a gemstone mine in the USA. It's hardness on the mohs scale is 7.5.

 

Ruby
Ruby is a blood-red gemstone of the mineral corundum. The red color is caused by the presence of the element chromium. Other varieties of gem quality corundum are sapphires. The blood red color commands the highest premium. After color follows clarity, a clear stone will command a premium.  The Mogok Valley in Upper Myanmar (Burma) was the world's main source for rubies for centuries. Rubies have been mined in Thailand, Cambodia, Burma, India, Afghanistan, Pakistan. Lighter shades of rubies, (pink sapphires) are found in Sri Lanka. After WWII rubies were found in Tanzania, Madagascar, Vietnam, Nepal, Tajikistan, and Pakistan. Some rubies have been found in the US in Montana, North and South Carolina and Wyoming. Ruby is 9.0 on the Mohs scale and is the birthstone for July.

 

Sapphire
Sapphire is a gemstone variety of the mineral corundum. Trace amount of other elements such as iron, titanium, chromium, copper, or magnesium can give corundum blue, yellow, purple, orange, or green color. Chromium impurities will yield pink or red, making them ruby.  Padparadsha is a pinkish orange variety, representing the color of the lotus. Sapphire is 9 on the mohs scale making it an excellent jewelry gemstone.  It is found in Eastern Australia, Thailand, Sri Lanka, China (Shandong), Madascar, East Africa, and Montana, US. The quality of sapphire is based on hue, saturation, and tone. Hue is the  color of the gem, saturation refers to the brightness of the hue, and tone is the lightness to darkness of the hue. Most sapphires are heated to improve or enhance the color. It is the birthstone for September.

 

Sphene
Sphene is a very rare brilliant yellowish-green, green, orange or brown gemstone with a high lustre, also known as "titanite" due to its titanium content. The name "sphene" comes from the Greek word, "sphen", meaning "wedge", which alludes to the formation of its crystals. Due to its strong dispersion, when brilliant-cut, sphene can exhibit a fire similar to that of diamond. Sphene is 5 to 5.5 on the Mohs hardness scale. Sphene deposits are found in Brazil, Burma (Myanmar), India, Kenya, Madagascar, Mexico,Austria, Sriu Lanka (Ceylon) and the USA. Sphene is not generally treated or enhanced, though the color can be changed to red or orange by heating. Most sphene gemstones are untreated and naturally orange and reddish sphene is available.

 

Spinel
Spinel comes in various shades of red and pink, blue, yellow, green, brown, and black. It has a hardness of 7.5 - 8 on the mohs scale making it an excellent, durable gemstone for rings. It is found in Sri Lanka, Afghanistan, Burma, Vietnam, Tanzania, Kenya, and Madascar. The price of spinel has increased dramatically in the past ten years.

 

Sunstone
Sunstone is a plagioclase feldspar. When viewed from certain directions it exhibits a brilliant spangled appearance. The optical effect is due to reflections from inclusions of red copper. It is the official gemstone of Oregon and is also found in Southern Norway. Other locations in the US include, Delaware, Pennsylvania, North Carolina, New York, and Virginia. It can appear clear, yellow, red, green, blue, and copper shiller. It's hardness is 6.5 on the Mohs scale.

 

Tanzanite
Tanzanite is the blue/purple variety of the mineral zoisite. Tanzanite is strongly trichroic, meaning it can appear sapphire blue, violet and burgundy depending on crystal orientation. Tanzanite is usually a reddish brown in its rough state, requiring artificial heat treatment to bring out the blue violet. The mineral was named by Tiffany & Co.. after Tanzania, the country in which it was discovered. In 2002, The American Gem Trade Association chose Tanzanite as a December birthstone. Tanzanite is 6.5 on the Mohs scale.

 

Topaz
Pure topaz is colorless and transparent but is usually tinted by impurities. Typical topaz is wine, yellow, pale gray, reddish-orange, or blue brown. Orange topaz, or precious topaz, is the November birthstone, the symbol of friendship and the state gemstone of Utah. Imperial topaz is yellow, pink or pink-orange. Brazilian Imperial Topaz can have a bright yellow to deep golden brown hue. Blue topaz is the state gemstone of Texas. Naturally occuring blue topaz is quite rare. Typically, colorless or pale material is heat treated and irradiated to produce a more desired darker blue. Topaz is found in Russia, Afghanistan , Sri Lanka, Czech Republic, Germany, Norway, Pakistan, Italy, Sweden, Japan, Brazil, Mexico, Australia, Nigeria, and the US. It has a hardness of 8 on the Mohs scale.

 

Tourmaline
Tourmaline is found in a variety of colors. Iron-rich tourmalines are black to bluish black to deep brown. Magnesium-rich varieties are brown to yellow, and lithium-rich tourmalines are almost any color; blue, green, red, yellow, pink, etc. Bi-colored and multicolored crystals are common. They are usually green at one end and pink at the other. Watermelon tourmalines are green on the outside and pink inside.   Tourmalines are 7-7.5 on the Mohs scale.

 

Zircon
Zircon is a mineral belonging to the group of nesosilicates. It's chemical name is zirconium silicate. Zircon occurs in many colors such as yellow, red, pink, brown, blue, hazel, or black. It can also be colorless. The color of zircons can sometimes be changed by heat treatment. In geological settings, the development of pink, red, and purple zircon occurs after hundreds of millions of years. Zircon has a refractive index of 1.925 - 2.105. The refractive index of diamond is 2.42, thus making the brilliance of zircon almost as scintillating as a diamond. It's hardness on the mohs scale 7.5. Zircon is found in Western Australia, Cambodia, and Tanzania.