Emeralds, one of the Big 4 gemstones, are valued based on the 4Cs--color, clarity, cut, and carat--along with origin, treatment, and certification. Vibrant green, eye-clean emeralds with minimal inclusions and superior cuts command the highest prices. Colombian emeralds are the most prized, followed by Zambian and Brazilian varieties. Treatments like oiling are common, while untreated stones fetch premium prices. Certification from reputed labs adds value. Prices range widely, from $20 per carat for lower-quality stones to over $5,000 for top-grade gems.