Gemstone Buying Guide: What to Know Before You Buy

The 4 Cs apply to colored stones too: Color (most important factor), Clarity (inclusions are more accepted than in diamonds), Cut (proportions affect brilliance), and Carat weight. Always ask if a stone is natural, treated, or synthetic. Common treatments include heat (sapphire, tanzanite), irradiation (blue topaz), oiling (emerald), and dyeing (onyx, turquoise).

Get a certificate from a reputable lab (GIA, AGL, or Gubelin) for valuable stones. Buy from dealers with return policies. Price per carat increases exponentially with size for rare stones.

Country of origin affects value - Burmese rubies and Kashmir sapphires command premiums..