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.
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
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
- 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
(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.
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
(kg.), a unit of
weight equivalent to 1000 grams, or 2.2046226 pounds (avoirdupois),
or 32.150737 troy ounces.
(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.
(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).
obsolete term which generally is used to refer to diamond, emerald,
sapphire or ruby.
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