Coloured gemstones offer a world of beauty, rarity and mystical romance. Discover the vast array of gemstones available in a spectrum of colours:
	Ruby, Garnet (Almandite, Pyrope, Rhodolite), Rubellite Tourmaline, Spinel, Red Beryl, Carnelian, Imperial Topaz, Coral, Diamond
	Sapphire, Citrine, Garnet (Spessartite, Malaya), Amber, Shell Cameo, Fire Opal, Madeira Quartz, Imperial Topaz, Zircon, Chalcedony (Carnelian, Jasper), Diamond
	Sapphire, Citrine, Amber, Golden Beryl, Topaz, Chrysoberyl, Tourmaline, Zircon, Diamond
	Peridot, Garnet (Grossularite, Tsavorite, Demantoid), Tourmaline, Emerald, Green Beryl, Sapphire, Andalusite, Jade (Jadeite and Nephrite), Bloodstone, Zircon, Chrysoberyl, Chrome Diopside, Malachite, Aventurine Quartz
	Sapphire, Tanzanite, Indicolite Tourmaline, Iolite, Spinel, Aquamarine, Topaz, Zircon, Chalcedony (Chrysocola), Lapis Lazuli, Azurite, Turquoise, Amazonite, Diamond
	Iolite, Tanzanite, Lapis Lazuli, Sodalite
	Amethyst, Sapphire, Rhodolite Garnet, Spinel
	Tourmaline, Kunzite, Morganite, Sapphire, Topaz, Pearl, Rhodolite Garnet, Spinel, Coral, Shell, Rhodochrosite, Rhodonite, Diamond
	Smoky Quartz, Tiger's Eye Quartz, Sard, Amber, Andalusite, Tourmaline, Tortoise Shell, Diamond
	Sapphire, Onyx, Pearl, Coral, Hematite, Opal, Diamond
	Hawk's Eye Quartz, Pearl, Hematite, Opal
	Pearl, Opal, Moonstone, Jadeite, Ivory, Bone,
	Diamond, Sapphire, Zircon, Topaz, Beryl, Moonstone, Rock Crystal Quartz
Phenomenal Gems	Chrysoberyl (Alexandrite, Cat's eye), Sapphire (Colour change, Star), Opal, Garnet (Colour change), Ametrine, Tiger's Eye, Tourmaline (Bi-colour, Cat's eye)

January	Garnet
February	Amethyst
March	Aquamarine, Bloodstone
April	Diamond
May	Emerald
June	Pearl, Opal, Alexandrite
July	Ruby
August	Peridot
September	Sapphire
October	Tourmaline
November	Topaz
December	Zircon, Turquoise

The information herein outlines briefly factors affecting the grading of gemstones,
including:

• Colour - Hue / Tone / Saturation
• Clarity
• Cut
  
  

For any coloured gemstone, colour is usually the most important value-setting factor.

Hue: The pure spectral sensations of violet, blue, green, yellow, orange, red and various combinations of these. Hue also refers to the sensation of purple (between red and violet), which is not found in the sun's spectrum. There are 150 different hues, but only 31 hues are used in coloured stone grading.	Tone: The lightness to darkness of a colour sensation. Tone is divided into eleven steps from colourless to white through increasingly darker grays to black.	Saturation: The strength, purity or intensity of the hue present in a colour sensation. Saturation is assessed on a seven level scale from neutral to vivid.
	0 COLOURLESS   1 EXT. LIGHT   2 VERY LIGHT   3 LIGHT   4 MEDIUM-LIGHT   5 MEDIUM   6 MEDIUM-DARK   7 DARK   8 VERY DARK   9 EXT. DARK   10 BLACK	NEUTRAL BROWNISH/GRAYISH sl.BROWNISH/GRAYISH v.sl.BROWNISH/GRAYISH moderatelySTRONG STRONG VIVID

*A gemstone's colour is described in the following order: Tone/Saturation/Hue,
ie. "a medium,strong blue sapphire".

Clarity Grading

After colour, the second most important value-setting factor is clarity.

Clarity is a gemstone's relative freedom from inclusions and surface blemishes.
Inclusions can affect both appearance and durability. Transparent gems are
grouped into three Clarity Types:

GIA TYPE I	GIA TYPE II	GIA TYPE III	Visibility of inclusions to the unaided eye, under favorable lighting conditions.
VVS	...	...	Minute to not detectable
VS	VVS	...	Minor
SI1	VS	VVS	Noticeable to obvious
SI2	SI1	VS	Noticeable to obvious
...	SI2	SI1	Obvious to prominent
...	...	SI2	Obvious to prominent
I1	I1	...	Prominent (moderate affect on appearance or durability)
I2	I2	I1	Prominent (considerable affect on appearance or durability)
		...	Prominent (severe affect on appearance or durability)
I3	I3	I2	Prominent (severe affect on transparency or durability)
		I3	Prominent (severe affect on beauty, transparency and durability)

Gem deposit locations of the World

HARDNESS - The resistance of a substance to being scratched.

A series of ten common minerals were chosen by the Austrian minerologist
F. Mohs in 1824 as a scale, by comparison where the relative hardness can
be told. Diamond is rated 10 on the Mohs scale of hardness, 10 to 150 times
as hard as corundum (hardness of 9).

The following minerals arranged in order
of increasing hardness is known as the
Mohs scale of hardness:

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.	Talc Gypsum Calcite Fluorite Apatite Orthoclase Quartz Topaz Corundum Diamond Comparison of Mohs relative hardness scale and absolute measurements of hardness *Diamond is extremely hard and cannot be plotted on this graph
	Consumer Facts: - A hardness of 7 and higher is recommended for gemstones worn in jewellery.
	- Gemstones with hardness greater than 5.5 can scratch glass.

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