Jewelry & Precious Metals
3 items
Standardized jewelry sizing and precious metal purity metrics: gold karat fineness percentages and European hallmarks (24K, 18K, 14K, 10K, 925 Silver, 950 Platinum), GIA diamond carat to millimeter diameter conversion tables, and standard necklace chain length categories.
Items (3)
CompareDiamond Carat to Millimeter Sizes
9 specs
Diamond carat weight is standardized under the Gemological Institute of America (GIA) where 1.00 metric carat equals exactly 0.200 grams (200 milligrams / 100 points). For an ideal 'Triple Excellent' round brilliant cut, carat weight translates into exact face-up millimeter diameters, from 0.10 ct (3.0 mm) to 3.00 ct (9.4 mm).
Gold Karats & Fineness Hallmarks
8 specs
Precious metal fineness is standardized under ISO 9202 and national hallmark regulations in parts per thousand (millesimal fineness) and traditional karats (24ths of pure gold), defining the exact alloy ratios of pure 24K (999), 18K (750), 14K (585), 10K (417), Sterling Silver (925), and Platinum (950).
Standard Necklace Chain Lengths
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Necklace and pendant chains are standardized in the jewelry industry in 2-inch increments into five standard anatomical resting categories: Collar (14 inches / 36 cm), Choker (16 inches / 41 cm), Princess (18 inches / 46 cm), Matinee (20–24 inches / 51–61 cm), Opera (28–36 inches / 71–91 cm), and Rope (40+ inches / 102+ cm).