Gemstones are described by gemologists using technical
specifications. Gems have refractive index, dispersion, specific
gravity, hardness, cleavage, fracture, and lustre. Some minerals that
are too soft to be generally applied in jewelry may still be
considered a gemstone because of their remarkable color, lustre or
other physical properties that have aesthetic value. Crystals and
gemstones are a marvel of nature- in there perfect geometrical
structures. Only five types of gemstones were considered precious:
diamond, ruby, sapphire, emerald, and amethyst.
A gemstone, gem or precious /semi-precious stone is a highly
attractive and valuable piece of mineral, which when cut and polished
is used in jewelry or other adornments. Although the different stones
formally have the same chemical composition, they are not exactly the
same. Color is the most obvious and attractive feature of gemstones.
A diamond is a transparent crystal of tetrahedrally bonded carbon
atoms and crystallizes into the face centered cubic diamond lattice
structure. Toughness relates to a material's ability to resist
breakage from forceful impact. The most familiar usage of diamonds
today is as gemstones used for adornment. Television ads portray them
as the ultimate gift of love. Magazine ads want us to believe that a
diamond is the only perfect gift to express love. If you plan on
purchasing a diamond because you like how it looks or if gives you or
your love one pleasure then by all means buy it but also consider it
as a form of investment.
Emerald is a variety of the mineral beryl, colored green by trace
amounts of chromium and sometimes vanadium. The name emerald comes
from the Greek 'smaragdos' via the Old French 'esmeralde', and really
just means 'green gemstone'. Colombia continues to be at the top of
the list in terms of the countries in which fine emeralds are found.
The magnificent green of the emerald is a colour, which conveys
harmony and love of nature. The value of an emerald depends on cut,
color, clarity, and carat. The colours do not occur until traces of
some other element are added.
A Ruby is a red variety of the gemstone corundum, the color caused
mainly by chromium. A ruby appears red because it absorbs all the
other colors of white light - blue, yellow, green, etc. The fewer the
number and the less obvious the imperfections, the more valuable the
ruby is. Although pieces of red corundum can be found weighing many
kilograms, they are generally not of sufficient quality to be
valuable as gemstones.
Sapphire is the non red variety of the mineral corundum, an aluminium
oxide. Some natural sapphires can be found as completely transparent,
or "white. Sapphire includes any gemstone quality varieties of
the mineral corundum except the fully saturated red variety, which is
instead known as ruby. The value of a star sapphire depends not only
on the carat weight of the stone but also the body color, visibility
and intensity of the asterism. Color changes may also be pink in
daylight to greenish under fluorescent light. Australia leads the
world in sapphire production.
No matter the gemstone they look best in jewelry, which uses gold
as a base. Although the price of some platinum group metals can be
much higher, gold has long been considered the most desirable of
precious metals, and its value has been used as the standard for many
currencies (known as the gold standard) in history. Blue gold can be
made by alloying with iron and purple gold can be made by alloying
with aluminium, although rarely done except in specialized jewelry.
Alternative white gold alloys are available based on palladium,
silver and other white metals (World Gold Council), but the palladium
alloys are more expensive than those using nickel.