Shopping for Fine Gems in Jewelry
Identifying precious and semi-precious gemstones in fine jewelry
A primer on identifying the colored gemstones used in fine jewelry. Knowing what you're looking for and what you're looking at when shopping empowers the buyer.
Third in a three-part series, we finally come to precious and semi-precious gemstones; treasures of brilliant, scintillating color.
Precious Gemstones
Gemstones come in a dazzling variety of colors, the most popular being red, blue, and green. The popularity of these colors probably has to do with the fact that the three stones classified as ‘precious’ by gemologists are ruby, sapphire, and emerald.
While ruby is always red, most jewelry “hunters” don’t know that sapphires come in several colors, including orange, pink and purple; and emeralds are only one color variation of beryl, a type of stone which also occurs in red (bixbite); yellow (heliodor); blue-green (aquamarine); pink (morganite), and colorless (goshenite).
Another gem has recently been added to the ‘precious’ category by many gemologists – tanzanite, a beautiful stone with a deep blue color with red to purple flashes.
It is found in only one place on Earth; Tanzania, Africa. High demand and low mine output has, in the past few years, made the cost-per-carat of tanzanite reach the ranges paid for very fine rubies, sapphires and emeralds.
Semi-Precious Gemstones
Of the gems considered semi-precious, some of the best-known and most popular are topaz, quartz, and garnet.
Topaz comes in the natural colors of white (or clear); and orange-gold, called imperial topaz, which is rare and expensive. But white topaz is most often heat-treated to create various non-naturally-occurring colors as a range of blues from light sky blue to deep, dark royal blue; also pink, green, red, and polychromatic (“mystic” topaz).
Quartz comes in many natural colors such as purple (amethyst); yellow-orange (citrine); bright orange (Madeira citrine); brown (smoky quartz); sunny yellow (lemon quartz); opaque pink (rose quartz); and white or colorless (rock crystal).
A heat-treated form of amethyst is prasiolite, which, after treatment, turns into a light mint green to a dark yellow-green.
Most folks even passingly familiar with gems know garnet to be a wine-red stone, but it also comes in a natural deep green (tsavorite garnet), and orange (hessonite garnet).
Other gems commonly used in jewelry include tourmaline, which comes in red, blue, blue-green, green, and pink, plus several shades in-between; and spinel, which comes in virtually all colors a gemstone can be – red, blue, green, yellow, pink, purple, orange, even black.
A natural-colored lime-green gemstone, peridot, is also popular. Then there are the popular opaque stones such as opal, jade and agate.
Varieties of opal include white opal (white body with multi-color flashes inside); black opal (black body with multi-color flashes inside); jelly opal (opal found in matrix with another stone); and fire opal (bright orange).
Jade of course comes in the traditional and natural green, but it can also be color-enhanced to produce red, lavender, yellow, light blue and black.
Almost all colored gemstones are heat-treated to lighten, darken or change their color or improve clarity. Among the most popular stones, only garnets, spinels and peridot are not subjected to color-enhancements, as their colors are completely natural.
Other treatments may be applied to lessen imperfections, hide cracks and fissures, and to improve appearance. A retailer should always tell you, and provide in writing, any and all information about gemstone treatments before purchase. Treatments may increase the value of a gem, but some treatments require special care.
Hopefully, these articles about what to look for when shopping for fine quality jewelry will provide a basic foundation that the savvy shopper can build on with more research and experience. Finding that one special piece where quality, beauty and price come together for an unforgettable purchase will make that piece the object of your heart’s most treasured desire.
