A gemstone is a mineral, rock (such in the case of lapis lazuli), or petrified material that when cut or faceted and polished is collectible or can be used in jewelry. Gems are classified into different groups, species, and varieties. Traditionally, common gemstones were classified into precious stones and semi-precious stones.
Any of several gems, including the diamond, emerald, ruby, and sapphire, that have high economic value because of their rarity or appearance are grouped as precious stone.
Difference Between Rati and Carat
1 Carat = 200 milligrams
Carat: “The unit of weight by which a diamond and gemstone is measured. One carat equals 200 milligrams, or 0.2 grams. The word comes from the carob bean, whose consistent weight was used in times past to measure gemstones”. This is a standard unit to weigh gem stones.
1 Ratti = 182 milligrams
Ratti: The unit used for weighing gemstones, particularly in India especially in Delhi and some other places.