Precious Stones

Diamond

DIAMOND

A diamond – from the ancient Greek ἀδάμας – adámas, meaning “unbreakable,” “proper,” or “unalterable”- is one of the best-known and most sought-after gemstones. Diamonds have been known to mankind and used as decorative items since ancient times; some of the earliest references can be traced to India.

The hardness of diamond and its high dispersion of light – giving the diamond its characteristic “fire” – make it useful for industrial applications and desirable as jewelry. Diamonds are such a highly traded commodity that multiple organizations have been created for grading and certifying them based on the four Cs, which are carat, cut, color, and clarity. Other characteristics, such as presence or lack of fluorescence, also affect the desirability and thus the value of a diamond used for jewelry.

Perhaps the most famous use of the diamond in jewelry is in engagement rings, which became popular in the early to mid 20th century due to an advertising campaign by the De Beers company, though diamond rings have been used to symbolize engagements since at least the 15th century.

Ruby

RUBY_3

A ruby is a pink to blood-red colored gemstone, a variety of the mineral corundum (aluminium oxide). The red color is caused mainly by the presence of the element chromium. Its name comes from ruber/rubeus, Latin for red. Other varieties of gem-quality corundum are called sapphires. The ruby is considered one of the four precious stones, together with the sapphire, the emerald, and the diamond.

Prices of rubies are primarily determined by color. The brightest and most valuable “red”, called pigeon blood-red, can be found only in Burma, and commands a large premium over other rubies of similar quality. After color follows clarity: similar to diamonds, a clear stone will command a premium, but a ruby without any needle-like rutile inclusions may indicate that the stone has been treated. Cut and carat (weight) are also important factors in determining the price.

Emerald

EMERALD_2

Emerald is a variety of the mineral beryl colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5–8 on the 10 point Mohs scale of mineral hardness. Most emeralds are highly included, so their toughness (resistance to breakage) is classified as generally poor.

The word “Emerald” is derived (via Old French: Esmeraude and Middle English: Emeraude), from Vulgar Latin: Esmaralda/Esmaraldus, a variant of Latin Smaragdus, which originated from the Greek word “σμάραγδος” (smaragdos=green gem).

Scientifically speaking, color is divided into three components: hue, saturation and tone. Emeralds occur in hues ranging from yellow-green to blue-green, with the primary hue necessarily being green. Yellow and blue are the normal secondary hues found in emeralds. Only gems that are medium to dark in tone are considered emerald; light-toned gems are known instead by the species name green beryl. The finest emerald are approximately 75% tone on a scale where 0% tone would be colorless and 100% would be opaque black. In addition, a fine stone should be well saturated, the hue of an emerald should be bright (vivid).

Sapphire

SAPPHIRE_2

Sapphire is a gemstone variety of the mineral corundum, an aluminium oxide. Trace amounts of other elements such as iron, titanium, chromium, copper, or magnesium can give corundum blue, yellow, purple, orange, or a greenish color. Chromium impurities in corundum yield a pink or red tint, the latter being called a ruby.

Commonly, sapphires are worn in jewelry. Is a natural gemstone but they also may be manufactured for industrial or decorative purposes in large crystal boules. Because of the remarkable hardness of sapphires, 9 on the Mohs scale, sapphires are used in some non-ornamental applications, including infrared optical components, such as in scientific instruments; high-durability windows; wristwatch crystals and movement bearings; and very thin electronic wafers, which are used as the insulating substrates of very special-purpose solid-state electronics (most of which are integrated circuits).

From all sapphires only the Blue are named as precious.