GemAs

Gemas are minerals, rocks, or organic substances that are valued for beauty, rarity, and durability. They are used in jewelry, ornamentation, and as collectors' items. The English term gemstone is commonly used, with gemas referring to the same concept in Spanish and Portuguese.

Most gemas form through geological processes deep underground or in sedimentary environments. Mineral gemas include diamond, ruby, emerald, and sapphire; other precious minerals include opal, turquoise, and garnet. Organic gemas include pearl, amber, and jet; some materials such as lapis lazuli are rock-based.

Properties used to evaluate gemas include hardness, color, clarity, and cut. The Mohs scale indicates scratch resistance; refractive index and dispersion affect brilliance; inclusions and zoning influence value. Because value depends on rarity and demand, "precious" vs "semi-precious" is traditional and debated.

Gemmas may occur naturally or be produced synthetically in laboratories. Common treatments modify color or clarity, such as heat treatment for sapphires and rubies, irradiation, or fracture filling. Lab-grown gems offer similar physical properties but with known origin.

Pricing and grading are guided by standards from laboratories like GIA or IGI, using the 4Cs: color, clarity, cut, and carat weight. Responsible sourcing and disclosure of treatments are emphasized in modern markets. Proper care includes cleaning with mild soap and water, avoiding harsh chemicals, and storing gems separately to prevent scratching.