General Info

Value
The value of a gemstone is directly related to it's rarity. The size or weight of the stone, it's color and clarity are all valued ultimately on rarity. Colorless diamonds for example, are valued more highly than yellow or brown diamonds, simply because colorless diamonds are more rare. Larger stones are valued higher than smaller stones, simply because larger stones are harder to find than smaller, and generally are more costly per carat. Supply and demand also have an effect on value. Many gemstones are found only in places where the climate (physical, economical and political) is hostile or unstable. This directly affects supply, and as a supply of a gemstone dwindles, it becomes harder to find.

Specific Gravity [SG]
Specific gravity of a substance is a measure of its density [weight per given volume] as compared to water. A substance with a specific gravity of 1.00 is exactly as dense as water. A higher specific gravity means that the substance is more dense than water, while a specific gravity of less than 1.00 means that the substance is less dense than water. Most gemstones have a specific gravity of between 3 and 4, thus are three to four times denser than water. The value of a gemstone is not typically determined by its specific gravity. This measure is useful primarily in distinguishing between different types of minerals with similar optical characteristics.

Refractive Index [RI]
The refractive index is a measure of the degree to which light is refracted [bent] as it through a particular stone. Light rays are deflected when they pass from on air [or other medium] into a gemstone, and the measure of this deflection can be used to identify the gem material.

The refractive index is also used in determining how to shape a gemstone. If the RI is known, the gem cutter can adjust the angles at which facets are ground onto the stone to maximize the effect of reflected and refracted light within the stone.

Hardness
If one substance will scratch another, the first substance is said to be the harder of the two. A subjective scale to rate the relative hardness of mineral specimens was developed by Frederick Mohs in the early 1800's. This scale, named for its creator, is still used today. The Mohs scale ranks minerals on a scale of one to ten, based on the ability of the higher-rated materials to scratch the lower-rated materials. The minerals used in the Mohs scare are:

Photographs and descriptions
We make every attempt to ensure that the photographs and descriptions of gemstones are as accurate as possible, however no photographic process or digital scanner is perfect. The photographs however, in GIF format cannot hope to match the beauty of seeing the gemstone in person. What this means, is that if the gemstone looks good here in a GIF file, it will look great when it arrives at your door. The gemstones as pictured are not to scale.