Petrozello Fine Jewelry :: Online Jewelry Store :: Gemstone, Pearl, & Color Information Chart

Information Source: Gem Reference Guide. Gemological Institute of America, 1995.

Gemstone/ Origin	Description	Treatment	Effects	Care	Cleaning
Amethyst (quartz) / Natural	Purple through bluish purple	Heat treatment	Lightens the color of very dark amethyst; removes smoky component of color	None	Ultrasonic: Usually safe Steamer: Risky Warm Soapy Water: Safe
Aquamarine (beryl) / Natural	Greenish blue through blue-green	Heat treatment	Produces blue from green, iron-colored material	None	Ultrasonic: Usually safe, unless stone contains feathers or liquid inclusions Steamer: Usually safe, unless stone contains feathers or liquid inclusions Warm Soapy Water: Safe
Black Cultured Pearl / Organic	Contains body colors of black, dark gray, or dark tones of blue, purple, green, or bronze	Irradiation	To produce "black" pearls (also gray or blue gray) from bleached pearls	Wipe with very soft cloth after each wearing	Ultrasonic: Never Steamer: Never Warm Soapy Water: Safe for more thorough cleaning (if strung, be sure string is completely dry before washing)
Blue Quartz / Lab Created	Meduim sky blue
Blue Topaz / Natural	Very slightly greenish blue to greenish blue	Irradiation	Produces a blue color in irradiated stones	Avoid heat and prolonged exposure to strong light; if radioactive (rare), avoid handling and wear	Ultrasonic: Never Steamer: Never Warm Soapy Water: Safe
Citrine (quartz) / Natural	Yellow through orange	Heat treatment	Produces citrine from amethyst	Avoid steam	Ultrasonic: Usually safe Steamer: Risky Warm Soapy Water: Safe
Created Ruby (synthetic corundum) / Lab Created	Very strong orangy red	Quench cracking (heating and then plunging it into cold water)	Produces cracks which imitate natural breaks and fingerprint inclusions	Avoid rough wear	Ultrasonic: Usually safe, but never for oiled stones Steamer: Usually safe, but never for oiled stones Warm Soapy Water: Safe, but avoid strong detergents and vigorous scrubbing on oiled stones
Cubic Zirconia (synthetic) / Lab Created	Colorless	None		None	Ultrasonic: Safe Steamer: Safe Warm Soapy Water: Safe
Cultured Pearl / Organic	Translucent to opaque	· Bleaching · Dyeing	· Bleach dark spots of conchiolin that show through the nacre · To alter the body color or hide colored blemishes	Wipe with very soft cloth after each wearing	Ultrasonic: Never Steamer: Never Warm Soapy Water: Safe for more thorough cleaning (if strung, be sure string is completely dry before washing)
Emerald (beryl) / Natural	Very strongly bluish green through green	Oiling (oil may contain green dye)	Hides flaws, improves transparency, may deepen color	Keep away from strong solvents, heat, and ultrasonic cleaners	Ultrasonic: Never Steamer: Never Warm Soapy Water: Generally safe, but avoid strong detergents and vigorous scrubbing on oiled stones
Garnet (pyrope) / Natural	Red through slightly purplish red	None known		None	Ultrasonic: Usually safe Steamer: Risky Warm Soapy Water: Safe
Iolite / Natural	Violet-blue through slightly violet-blue	None known		None	Ultrasonic: Risky Steamer: Risky Warm Soapy Water: Safe
Mother of Pearl (shell) / Organic	Translucent to opaque	Dyeing	To produce a variety of colors	Avoid solvents and prolonged exposure to strong light	Ultrasonic: Risky Steamer: Risky Warm Soapy Water: Safe
Mount St. Helens / Lab Created	Deep, clean bluish green
Mystic Fire Topaz / Natural	Greenish	Coated	Changes clear topaz to color	Normal	Ultrasonic: Unsafe Steamer: Unsafe Warm Soapy Water: Safe
Onyx (chalcedony) / Natural	Solid black color	Dyeing	Chalcedony is dyed to practically all colors for various uses; the bands in agate and onyx accept dye differently so that a green dye, for example, may impart color to some layers and leave others white	None	Ultrasonic: Usually safe Steamer: Usually safe Warm Soapy Water: Safe
Peridot / Natural	Yellowish green through greenish yellow	No commercial treatments known		None	Ultrasonic: Risky Steamer: Never Warm Soapy Water: Safe
Pink Sapphire (corundum) / Natural	Red through purple	Coating with a thin film	Creates, deepens, or changes the color of a sapphire	Avoid abrasions	Ultrasonic: Usually safe Steamer: Usually safe Warm Soapy Water: Safe
Pink Tourmaline / Natural	Red-orange through reddish purple	Irradiation	Produces a deep pink to red to deep purple from very light pink, green, blue, or colorless	None	Ultrasonic: Risky Steamer: Risky Warm Soapy Water: Safe
Rhodolite Garnet / Natural	Slightly purplish red through reddish purple	None known		None	Ultrasonic: Usually safe Steamer: Never Warm Soapy Water: Safe
Ruby (corundum) / Natural	Orange-red through strongly purplish red	Heat treatment	Removes purple or brownish color component	None	Ultrasonic: Usually safe, but never for oiled stones Steamer: Usually safe, but never for oiled stones Warm Soapy Water: Safe, but avoid strong detergents and vigorous scrubbing on oiled stones
Sapphire (corundum) / Natural	Violet-blue through greenish blue	Heat treatment	Produces blue sapphire from milky "gueda" sapphire	None	Ultrasonic: Usually safe Steamer: Usually safe Warm Soapy Water: Safe
Tanvorite / Lab Created	Deep, clean bluish/purple
Tanzanite (zoisite) / Natural	Bluish purple and violet through blue	Heat treatment	Produces tanzanite colors in certain crystals with initially brownish colors	None	Ultrasonic: Never Steamer: Never Warm Soapy Water: Safe