Emeralds from the Swat valley are known for a vivid, slightly bluish green and are usually found in smaller sizes. Colombian emeralds are celebrated for a warm, pure green and larger crystals.
Origin alone does not set the price. Colour, clarity and size matter more, and almost every emerald contains natural inclusions, often described as its garden.
Most emeralds are treated with oil or resin to improve clarity. Ask what treatment a stone has had; untreated stones of good colour are rare and priced accordingly.