The Diamond is the birthstone of April and the anniversary gemstone for the 10th and 60th years of marriage.

 Diamonds were discovered in India in 500 B.C., and the name "diamond" comes from the Greek word "Adamas" which means unconquerable - suggesting the eternity of love. Since ancient Greece, diamonds have been the traditional symbol of love, and the ancients believed they were hardened dew drops, splinters from the stars or crystallized lightning. A diamond is the hardest substance known to humankind, and is made of a crystallized carbon that has unique powers of light reflection. Since diamonds are composed of a single element, they are the purest of all gemstones.

Diamonds are a wonder of nature. Their cold sparkling fire has held us spell-bound for centuries, inspiring rich passionate myths of romance, intrigue, power, greed, and magic. Ancient Hindus, finding diamonds washed out of the ground after thunderstorms, believed they were created by bolts of lightning. In our place and time, the diamond is a symbol of enduring love, and often grace engagement rings.

There are many kinds of diamonds: transparent, translucent or opaque; ranging from colorless to sooty black, with many colors in between. Mostly transparent diamonds, colorless or tinted, are used as jewelry. Others are used widely in industry. The color of a diamond depends on the kind of impurities embedded inside it. Yellow diamonds, for example, betray minute quantities of nitrogen, while boron imparts a bluish hue.

Some diamonds seem to have lived lives of their own. One legendary stone of the diamond hall of fame is the Koh-i-noor diamond. The Koh-i-noor's early history is shrouded in time. It is believed to be 5,000 years old, and was featured in the great Sanskrit epic "The Mahabharata". Originally owned by the Rajah of Malwa in India, the Koh-i-noor has since been a player in victories and defeats spanning India, Persia and Afghanistan. It was in the possession of the great Mogul dynasty from 1526 to 1739, its owners included Shah Jehan who built the Taj Mahal in memory of his queen Mumtaz. The Persian invader Nadir Shah briefly possessed it until his assassination in 1747. The jewel then fell into the hands of Afghan rulers who eventually surrendered it to the Rajah of Punjab, Ranjit Singh.

Two years after Ranjit Singh's death in 1839, Punjab became part of India under British rule. The stone was presented to Queen Victoria who had it cut from its original 187 carats to 108 carats in an attempt to further enhance its beauty. After her death, the diamond became part of the British Regalia, and was worn by Queen Elizabeth, the Queen Mother in her 1937 coronation. Today, the Koh-i-noor diamond is worn as a brooch by the Queen Mother on ceremonial occasions.

Diamond is the ultimate gemstone, having few weaknesses and many strengths. It is well known that diamond is the hardest substance found in nature, but few people realize that diamond is four times harder than the next hardest natural mineral, corundum (sapphire and ruby). But even as hard as it is, it is not impervious. Diamond has four directions of cleavage, meaning that if it receives a sharp blow in one of these directions it will cleave, or split. A skilled diamond setter and/or jeweler will prevent any of these directions from being in a position to be struck while mounted in a jewelry piece.

As a gemstone, Diamond's single flaw (perfect cleavage) is far outdistanced by the sum of its positive qualities. It has a broad color range, high refraction, high dispersion or fire, very low reactivity to chemicals, rarity, and of course, extreme hardness and durability.

Properties
In terms of it's physical properties, diamond is the ultimate mineral in several ways:

Hardness: diamond is a perfect "10", defining the top of the hardness scale.
Clarity: diamond is transparent over a larger range of wavelengths (from the ultraviolet into the far infrared) than is any other substance
Thermal Conductivity: diamond conducts heat better than anything - five times better than the second best element, Silver!
Melting Point: diamond has the highest melting point (3820 degrees Kelvin)!
Lattice Density: The atoms of diamond are packed closer together than are the atoms of any other substance!