Chrysoprase Buying Guide
Chrysoprase Buying and the Four Cs
Chrysoprase is a green variety of chalcedony, a non-crystalline quartz. Colored by tiny inclusions of pimelite, this is a rare example of a green gem whose color arises from nickel. Chromium, which imparts a green hue in emerald, can also create green chalcedony. However, this chrome chalcedony constitutes a distinct gem variety from chrysoprase.
Gemologists describe color using hue, tone, and saturation. For chrysoprase, the primary hue is green, and top-color gems are a bright, apple green. Secondary hues of yellow or blue may be present. However, secondary yellow hues are undesirable. Top-quality specimens won’t show these. Slight blue hues are more preferable. Some chrysoprase may even be blue-green or aqua in color.
In chrysoprase, medium to medium-dark tones are ideal. This allows for a brightly saturated gem. Lighter tones can appear washed-out, and darker tones never reach the saturation of a medium-toned specimen. Sometimes, darker-toned chrysoprase is referred to as “prase.”
Clarity and Transparency
Because of the material’s abundance, chrysoprase should have excellent clarity. Thus, inclusions shouldn’t be visible to the eye. However, dendritic inclusions are sometimes present. For certain jewelry projects, their fractal, tree-like appearance may be quite desirable.
Because chalcedony is made of microcrystals, it doesn’t achieve the transparency of crystalline quartz. Instead, it’s semi-translucent to opaque and often appears milky. Among chrysoprases of the same color, transparency will determine the better specimen. In top-quality specimens, the translucence will even rival jade. However, larger and thicker pieces tend to be more opaque.
Chrysoprase, like other non-transparent gems, is generally cut en cabochon. Due to its abundance, lapidaries should cut away inclusions to create a flawless gem.
Some chrysoprase pieces are carved. For example, cameos, figurines, and abstract shapes are common uses of this gem. For such pieces, workmanship and artistic merit impart greater value than the stone itself.
Large pieces of chrysoprase are available, and carat weight doesn’t have a large impact on per-carat price. However, large gems are less likely to display translucence. Thus, a large, translucent chrysoprase is a rarity that may come with a premium on price.
Does Chrysoprase Fade in Sunlight?
Some people have reported that this gem’s color fades upon exposure to heat and sunlight, but lapidary Howard Denghausen hasn’t noticed any fading. The difference? The material’s origin.
While chrysoprase from European mines can fade and dry out in the sun, gems from Australia won’t. Nevertheless, exposure to excessive sunlight and heat isn’t recommended. To keep your chrysoprase jewelry looking great, store it in a dark jewelry box and reserve any European chrysoprase pieces for evening wear. If your jewelry does fade, try using a moist cloth to restore color.
Being a porous stone, dyed chrysoprase is readily available. Dyed specimens have bright, saturated color and are less expensive than untreated gems. However, some dyes can fade in sunlight or wash away with water. Still, dyed chrysoprase can be a great way to bring color to your jewelry.
Chrysoprase as a Jade Imitation
Very fine examples of chrysoprase can rival jade in color and translucence. Hence, chrysoprase can serve as a jade imitation, and some dealers use the misnomer “Australian jade” to refer to chrysoprase. While the imitation may convince non-experts, a gemologist or jeweler should be able to tell the difference between jade and chrysoprase. Fibrous structures, seen by shining a bright light through the stone, indicate that the gem is jade.