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.
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/JPEG 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/JPEG file, it will look great when it arrives at your door.
For Mineral Ores we have the accurate Chemical Analysis data Sheets for each industrial minerals we can supply.All our Minerals are tested with state of the Art Technology Mineral Organization - SEAMIC based in Dar es Salaam.
Unlike Diamond certificates, which have an international certification standard (GIA), there is no corresponding internationally recognized certification for colored gemstones. We do issue Gemstones Certificate the charge is USD 20 per single stone.Our Gems are certified also by SEAMIC.
- Blemish, a defect in a gemstone found at the surface, such as a pit, nick, scratch, chip or even an extra facet where none should be.
- Calibrated, a gemstone whose dimensions are a standard (mm) size, and are cut to fit ready made jewelry pieces.
- Carat (ct.), unit of weight. 1 carat is equivalent to 0.2 grams. Carat weight should not be confused with the term karat (kt.), which is used to measure the quality of gold, nor carrot which refers to a plant. The abbreviation (cwt.) is used to indicate the total weight of two or more gemstones, such as the weight of a parcel of stones, or a pair of stones often traded as a group. Carat weight should not be used to judge the size of a stone, as differences in cutting and the depth of a stone can allow stones of the same weight to have different dimensions. Also, the density, or specific gravity of different materials can have the same effect. A one carat sapphire for instance is much smaller than a one carat opal. When looking for a setting for a particular gemstone, the stones dimensions in millimeters should be used, not the carat weight.
- Grain, unit of weight, 1 grain is equivalent to 0.32399455 carats, or 1/24 pennyweight. The term is sometimes used to approximate a quarter carat.
- Gram, unit of weight in the Metric system. 1 ounce (avdp.) is equivalent to 28.349523 grams (141.747615 ct.). Rough (uncut) material is often sold by the gram, whereas cut or finished gemstones are generally sold by the carat.
- Hardness, measured by the Mohs scale (1-10), after the mineralogist Friedrich Mohs (1773-1839).
Inclusion, an inclusion within a gemstone is an internal flaw, or included crystal, bubble, cloud, graining, fracture, etc.. Inclusions are different from blemishes, which are imperfections at the surface of the gemstone. Inclusions are not always bad. Inclusions can be used like a finger print, to identify diamonds and other valuable gemstones.In some cases, inclusions can actually increase the brilliance of a gemstone. Beware of emeralds and rubies which do not contain inclusions, as these are extremely rare, and are probably synthetic.
Karat (K or Kt.), a measure of the amount of gold present in a gold alloy, expressed in 1/24ths.
Kilogram (kg.), a unit of weight equivalent to 1000 grams, or 2.2046226 pounds (avoirdupois), or 32.150737 troy ounces.
Millimeter (mm.), a measure of distance in the Metric system. 1 inch is defined as 25.4 millimeters. The metric system is the standard used in the jewelry industry, by gemologists, and by science worldwide.
Ounce (oz.), a particularly confusing set of units, used to measure weight and volume. There are two versions of ounces for weight, troy (also called apothecaries) and avoirdupois (common ounce).
Precious Stones, an obsolete term which generally is used to refer to diamond, emerald, sapphire or ruby.
Semi-precious Stones, also an obsolete term used to describe gemstones which are not diamond emerald, sapphire or ruby. These terms are misleading as many "semi-precious" gemstones are extremely valuable, and some "precious" gemstones are of such poor quality that their value is very low.