The value of an Emerald is determined by color, flawlessness, and size. Large flawless stones are scarce and very expensive and are rarely seen in jewelry stores. Emerald is a variety of Beryl. Columbia, Zimbabwe, Zambia, and Brazil are the principle sources. Brazil has found some particularly fine specimens.
Emeralds weighing more than several carats is extremely rare and costly.
Smaller sizes are more abundant and larger sizes are more valuable. Early gem merchants in India sought to purify the color of their Emeralds by immersing them in clear oils or paraffin. They found that clear oils and waxes rendered surface fissures nearly invisible to the naked eye. Today we have made sophisticated technologies with which to clarity enhance Emeralds. In addition to the oils and waxes of ancient methods, we now use clear resins to penetrate the open fissures surfacing in the gemstones.