Emerald is a green form of the mineral beryl. The name emerald is derived from a Persian word, which later appeared in Greek, smaragdos. Emeralds have been treasured for over 4,000 years since early Babylon. Emeralds have a long and rich history, and are found in such diverse places as Egypt, Columbia, Zambia and Russia.

Color and size are the primary value characteristics of emeralds. In some cases, origin also play s a part because the output from certain mines are prized above others. Emeralds are regularly heavily included but the most prized, and most expensive, are relatively free from inclusions. The optimum color is a rich pure green similar to the lens color on a traffic light.

The value of emeralds can vary hugely based on the assorted variables. Emerald can be bought for as little as $20/pound up to $500,000/ct.

.

Most emeralds in the marketplace have been treated using colored oils or resins that are soaked into the stone to help obscure the inclusions . Cedar wood oil is quite common for this usage because the refractive index is close to that of emerald but any liquid will suffice. This is done at the mine sites and is considered customary in the trade because it's done to virtually every stone. It is not considered an ‘enhancement' unless the material is colored and therefore changes the color of the stone, as well as the clarity. An oiled stone can be detected through microscopic examination.

Emerald is generally accepted as the birthstone for May.