RUBY Ruby is a variety of corundum, just like sapphire. All red corundums are called rubies, and every color besides red in the corundum family is a sapphire – the non-blue ones are called “fancy” sapphires. It is one of four precious stones along with sapphire, emerald, and diamond. Corundum is a very hard mineral, ranked 9 out of 10 on the Mohs scale, with only diamond above it at 10. “Ruby” comes from the latin word ruber, which means “red.” Ruby is frequently heat treated or dyed for color and clarity, and fractures and cracks may be filled. These treatments are accepted by the industry, though an all-natural ruby will always command a higher value. It is a July birthstone.
- RUBY ZOISITE / RUBY FUSCHITE Ruby zoisite, also known as Anyolite, is a combination of minerals: ruby (corundum), zoisite, and tschermakite – a mineral responsible for the black flecks often found in ruby zoisite. It is rare and often faked, or is actually ruby fuschite. Ruby fuschite looks similar but one way to tell the difference is that there may be a kyanite ring around the ruby in ruby fuchsite. Ruby zoisite may also have a scattering of black hornblende. Much of the material being sold as ruby zoisite is actually ruby fuchsite.
SAPPHIRE Sapphire is one of the precious gemstones, along with ruby, emerald, and diamond. It is typically thought of as blue but comes in many colors. It is a variety of the mineral corundum, just like ruby. In fact, all gem quality corundum that is not red is called sapphire. Sapphire that is any color besides blue is termed “fancy sapphire.” It is often heat treated for color and clarity, and occasionally fractures and cracks are healed or filled. These are industry accepted treatments.
SERPENTINE The name serpentine refers to a group of about 20 magnesium silicate minerals, rather than a single variety of gemstone. Thought to be named because of the green hues of the stones, it is often mistaken for jade because of its color and may be sold as “new jade.” Myth states that Romans used serpentine in the dark arts as well as in defense against sorcery. It was used in the creation of drinking vessels to protect the drinker from toxins. It may be dyed for color.
SODALITE Sodalite is typically a royal blue mineral with white veining. It is named for its sodium (“soda”) content. High quality sodalite is used as a gemstone. It may be confused with lapis lazuli as the two are similar, but unlike lapis, sodalite does not have pyrite inclusions. If significant pyrite is present, the specimen is not considered to be sodalite. Most sodalite will fluoresce orange under UV light! It may be dyed.
RHYOLITE Rhyolite is an igneous rock with a high silica content. It is made of quartz, plagioclase feldspar, and sanidine. It may have minor amounts of hornblende and biotite. Gem deposits are often found hosted in rhyolite. It can be confused with jasper.
- SONORAN DENDRITIC (RHYOLITE) Found in the state of Sonora, Mexico, this stone is simply called Sonora Dendritic – because of the dendritic patterns that give it such character. It can have scenic-looking pictures as part of its’ patterning. It was discovered in 2009 and it appears it was only first offered at a mineral show in 2011. It is a variety of rhyolite. It is not treated.
SPINEL Spinel is often thought of as black but also comes in blue, purple, red, orange, and pink. There are famous Spinel gems that have made a name for themselves in history. This includes the “Timur Ruby” in the Crown Jewels, weighing over 350 carats, and the “Black Prince’s Ruby,” which is displayed in the Tower of London and was said to have been given to Edward, Prince of Wales in 1367 after being owned by a succession of Moorish and Spanish kings. Spinel is a birthstone for August. Spinel may be heat treated for color, or fracture filled in fine gemstones, to improve clarity.
TANZANITE Tanzanite was discovered recently, in 1967, and is only found in one location in Tanzania, near Mt. Kilimanjaro. It was named and initially marketed by gemstone and jewelry powerhouse Tiffany Co. It has quickly become a very popular stone. It is commonly heated to improve its color, and this is an industry accepted standard.
TOPAZ Topaz is traditionally thought of as golden yellow, but more recently blue topaz has gained popularity. However, almost all blue topaz starts as colorless and is irradiated to achieve the hue. Topaz is rarely found blue in nature. It comes in many colors, colorless is called “white topaz”. Its name comes from the Greek name for an island in the Red Sea, which actually never produced topaz, but rather peridot – which was confused with topaz. Topaz is often treated with heat or irradiated to improve the color, this is an acceptable practice. Blue topaz is always the result of heat-treating colorless topaz. It is the birthstone for November (yellow) and December (blue). Blue topaz is the Texas state gemstone.
TOURMALINE Tourmaline is found in a huge range of colors. It is famous for its watermelon variety, which is pink, white, and green, and truly looks like sliced watermelon. However, tourmaline’s other colors are also valued. It is found in many countries, including the United States. Tourmaline is pleochroic, meaning it often displays different colors when viewed from different angles. The effect is more apparent in some stones than others. Occasionally it is heat treated or irradiated, to improve the color – an acceptable practice.
- INDICOLITE TOURMALINE Indicolite tourmaline is a blue to teal/aqua tourmaline, the rarest color of tourmaline. It is common and acceptable for this stone to be heat treated to improve its color.
TURQUOISE Turquoise, following the canonical precious gemstones, may be the most-loved stone we know of. It has been found in Egyptian tombs dating back to 4000BC and is highly esteemed by Native Americans in the Southwest United States, as well as by cultures in Central America. Turquoise is commonly subjected to a variety of treatments both to stabilize it, because it can be brittle, as well as to improve color and sheen. These treatments are considered acceptable. *Much of the turquoise on the market is composite – meaning it’s made of multiple pieces of turquoise that have been bonded together. The pieces are all genuine turquoise and thus the final piece is also considered genuine turquoise. It may sound like the resulting material is weak, but it is not. It is used commonly in jewelry.
- COPPER TURQUOISE Sometimes a copper or bronze metal is infused during the above process, creating copper turquoise, which may be called “Mojave” turquoise. Copper turquoise, like regular turquoise, may be natural colored or dyed colors like purple, green, and black.
- KINGMAN TURQUOISE The Kingman turquoise mine is located in Arizona, United States. Stone hammers found in the area suggest that Native Americans mined there as early as 600 AD. Kingman turquoise may have a white matrix that is often dyed black for better contrast, but the mine produces turquoise with a variety of matrix colors. The turquoise itself is best known for a sky blue color. It is stabilized and may be treated with the Zachery process, which is a preferred treatment for turquoise due to being practically undetectable.
- SLEEPING BEAUTY TURQUOISE Sleeping Beauty turquoise comes from the Sleeping Beauty mine in Globe, Arizona. About the mine: It is known for its mostly uniform, sky blue color and minimal matrix. It was named for the mountain range where it is located, which looks like a sleeping woman laying on her back. It was originally opened to collect copper and gold and the turquoise was a surprise. The Sleeping Beauty mine closed in 2012 leading to rising prices for this precious turquoise.
VARISCITE Variscite may be confused with turquoise, however it is greener in hue. It often grows alongside turquoise, and when it is too difficult to tell them apart, the gem dealer may call the material “variquoise.” The green color is caused by trace amounts of chromium. It is named for Variscia, Germany, now called Vogtland, where it was first found in 1837. It may contain white veins of crandallite. Variscite has also been called Utahlite. Variscite found in Nevada, United States often has black spiderwebbing, making it more easily confused for turquoise. Much of the Nevada variscite comes from mines in Lander county. There is a prominent mine called the New Lander mine, and variscite that comes from here may be erroneously called “New Lander Turquoise.” Variscite is porous and can be stained by sweat, perfumes, oils, etc. If wearing against the skin, clothing should be worn between the gem and the skin. It is often backed by a stabilizing material when cut into cabochon form. Variscite is not known to be treated, but other stones may be dyed to imitate variscite, so care should be taken when purchasing.
VESUVIANITE IDOCRASE / VESSONITE Vesuvianite, also called idocrase, is a silicate mineral that is found in many colors but often green, yellow, and brown. It was first discovered adjacent to lavas at Mount Vesuvius, providing the basis for its name which was given in 1795. It can be confused for jade because of its color. *Regarding confusion about the name: Stones termed vessonite are sometimes inferred to be a green variety of garnet. The name vessonite has been corrupted from the name Vesuvianite. There may also be some name confusion to due to a variety of garnet called Hessonite, and another, green-hued, garnet called Grossular (to which Vesuvianite has structural similarities). Grossular garnet and Vesuvianite (idocrase) may easily be confused. However, garnet and idocrase are different minerals. Therefore, any stone called vessonite is likely to be Vesuvianite. Otherwise it is most like a grossular garnet.
Much of the information in this post came from my personal knowledge. I also used www.Mindat.org, www.Gemdat.org, www.Geology.com, www.Minerals.net, Wikipedia, and of course www.GIA.edu. I recommend all of these sources as reliable and trustworthy.