Diamond (gemstone) Diamond (gemstone) A diamond (from the "adámas", meaning "unbreakable", "proper", or "unalterable") is one of the best-known and most sought-after gemstones. Diamonds have been used as decorative items since ancient times; some of the earliest references can be traced to 25,000 - 30,000 B.C. The hardness of diamond and its high dispersion of light—giving the diamond its characteristic "fire"—make it useful for industrial applications and desirable as jewelry. Diamonds are such a highly traded commodity that multiple organizations have been created for grading and certifying them based on the "four Cs", which are color, cut, clarity, and carat. Other characteristics,
Kimberlite tailings performance of fixed-bed kimberlite tailings was studied and the adsorption capacity was found to be 0.27 mg/g of adsorbent. Film diffusion was found to be the rate-limiting factor for the removal of arsenic by kimberlite tailings. Adsorption of arsenic was found to be pH dependent and higher removal efficiencies were observed near neutral pH range. The arsenic uptake increased with increase in adsorbent dose. Spent kimberlite tailings could be regenerated with dilute NaOH. The proposed treatment methodology was applied to the groundwater samples collected from various places of North 24-Parganas district situated in West Bengal, India. The samples were analyzed