Gem of the Month

Each month this section will feature either a topic of interest to gem lovers or one special gemstone with background on the material and its value.

Go to: Homepage -- what's new in faceted gems -- what's new in designer cabochons and gem carvings -- gem of the month -- gem of the month archive -- birthstone of the month -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- about the ACS cutters -- settings for these gems --faceting information -- purchase UltraTec equipment

 

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Scapolite

July, 2000

This gem, which is not widely available and little recognized by the public, is none the less, a desirable and attractive gem material for jewelers as well as collectors. It is known mineralogically as Wernerite, after its discoverer. Similar to the gems in the garnet group, this gem ranges in color and precise gemological values along a "solution series" as the amount of sodium and calcium in the chemical formula changes. Colors range from near colorless to yellow and orange, through pinks to purple. Yellows are the most commonly found colors with purple a distant second. Irradiation of colorless or yellow specimens can create a brownish purple variety which is prone to fading and not very attractive. The main sources are Brazil, Tanzania, Madagascar and Sri Lanka. Cat'seye stones are rather rare and desirable as they have exceptionally sharp eyes. Its hardness of 6 and cleavability necessitate some care in setting and wearing in jewelry, with daily wear ring use unwise. The name comes from the Greek "scapos" or rod, and refers to the short rod-like crystal habit.

 


Value

The value of yellow scapolite, depends on size, clarity and strength of color. The usual premium on value would be expected in terms of saturation of color and custom versus native or commercial cutting. Values for natural purple or irradiated stones differ dramatically as the natural stones are both rarer and a delicate, but much purer, purple. They would range above and below the prices for yellows, respectively. The rare cat'seye varieties are highly varied and quite beautiful.


Gemological Data:

Makeup: a complex silicate with different varieties differing in the amount of sodium and calcium present

Luster: Vitreous

Hardness: 6

Crystal structure: Tetragonal

Fluorescence: inert to strong pink, orange or yellow (LW and SW)

Cleavage: Perfect in two directions

Density: 2.70

RI: 1.54 -1.58

Birefringence: 0.020

Dispersion: 0.017


Stones Currently Available:

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Go to: Homepage -- what's new in faceted gems -- what's new in designer cabochons and gem carvings -- gem of the month -- gem of the month archive -- birthstone of the month -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- about the ACS cutters -- settings for these gems --faceting information -- purchase UltraTec equipment