{"openapi":"3.1.0","info":{"title":"Gemstone Weight API","version":"1.0.0","description":"Gemstone weight maths as an API, computed locally and deterministically — the carat, gram, point and measured-weight numbers a jeweller, gem dealer, appraiser or lapidary works to. The carat-to-grams endpoint converts a carat weight to grams, milligrams and points: the metric carat is exactly 0.2 g (200 mg) and is split into 100 points, so a 1.5 ct stone is 0.3 g and 150 points and a quarter-carat is a twenty-five pointer — the carat is a mass unit, not a size, so a 1 ct diamond and a 1 ct emerald weigh the same but look different because their densities differ. The grams-to-carat endpoint inverts it (divide grams by 0.2, or multiply by 5), for a weight taken on a gram balance. The round-brilliant-weight endpoint gives the trade estimate used when a stone is set and cannot be put on a scale: carat ≈ diameter² × depth × 0.0061, with the girdle diameter and total depth in millimetres — a 6.5 mm round about 4 mm deep estimates near 1 carat, which is exactly why a 1 ct round brilliant measures roughly 6.5 mm across; the factor can be nudged for a thick girdle or a different cut. Everything is computed locally and deterministically, so it is instant and private. Ideal for jewellery and appraisal tools, gem-dealer and auction apps, and lapidary calculators. Pure local computation — no key, no third-party service, instant. Weight maths only — it does not price the stone or grade the colour and clarity. 3 compute endpoints. For gold karat and fineness use a gold-purity API.","contact":{"name":"PremiumApi","url":"https://www.oanor.com/by/premiumapi"}},"servers":[{"url":"https://api.oanor.com/gemstone-api","description":"oanor gateway"}],"tags":[{"name":"Gemstone"},{"name":"Meta"}],"components":{"securitySchemes":{"oanorKey":{"type":"apiKey","in":"header","name":"x-oanor-key","description":"Get your key at https://www.oanor.com/developer/keys"}}},"security":[{"oanorKey":[]}],"paths":{"/v1/carat-to-grams":{"get":{"operationId":"get_v1_carat_to_grams","tags":["Gemstone"],"summary":"Carat to grams, mg and points","description":"","parameters":[{"name":"carat","in":"query","required":true,"description":"Carat weight","schema":{"type":"string"},"example":"1.5"}],"security":[{"oanorKey":[]}],"responses":{"200":{"description":"OK"},"401":{"description":"Missing or invalid x-oanor-key header"},"402":{"description":"Active subscription required"},"429":{"description":"Rate-limit or monthly quota reached"},"502":{"description":"Upstream did not respond"}}}},"/v1/grams-to-carat":{"get":{"operationId":"get_v1_grams_to_carat","tags":["Gemstone"],"summary":"Grams to carat and points","description":"","parameters":[{"name":"grams","in":"query","required":true,"description":"Weight in grams","schema":{"type":"string"},"example":"0.3"}],"security":[{"oanorKey":[]}],"responses":{"200":{"description":"OK"},"401":{"description":"Missing or invalid x-oanor-key header"},"402":{"description":"Active subscription required"},"429":{"description":"Rate-limit or monthly quota reached"},"502":{"description":"Upstream did not respond"}}}},"/v1/round-brilliant-weight":{"get":{"operationId":"get_v1_round_brilliant_weight","tags":["Gemstone"],"summary":"Estimated carat of a round brilliant","description":"","parameters":[{"name":"diameter_mm","in":"query","required":true,"description":"Girdle diameter (mm)","schema":{"type":"string"},"example":"6.5"},{"name":"depth_mm","in":"query","required":true,"description":"Total depth (mm)","schema":{"type":"string"},"example":"4.0"},{"name":"factor","in":"query","required":false,"description":"Weight factor (default 0.0061)","schema":{"type":"string"},"example":"0.0061"}],"security":[{"oanorKey":[]}],"responses":{"200":{"description":"OK"},"401":{"description":"Missing or invalid x-oanor-key header"},"402":{"description":"Active subscription required"},"429":{"description":"Rate-limit or monthly quota reached"},"502":{"description":"Upstream did not respond"}}}},"/v1/meta":{"get":{"operationId":"get_v1_meta","tags":["Meta"],"summary":"Spec","description":"","parameters":[],"security":[{"oanorKey":[]}],"responses":{"200":{"description":"OK"},"401":{"description":"Missing or invalid x-oanor-key header"},"402":{"description":"Active subscription required"},"429":{"description":"Rate-limit or monthly quota reached"},"502":{"description":"Upstream did not respond"}}}}},"x-oanor-pricing":[{"slug":"free","name":"Free","price_cents_month":0,"monthly_call_quota":7300,"rps_limit":2,"hard_limit":true},{"slug":"starter","name":"Starter","price_cents_month":760,"monthly_call_quota":62000,"rps_limit":6,"hard_limit":true},{"slug":"pro","name":"Pro","price_cents_month":2580,"monthly_call_quota":252000,"rps_limit":15,"hard_limit":true},{"slug":"mega","name":"Mega","price_cents_month":7900,"monthly_call_quota":1190000,"rps_limit":40,"hard_limit":true}],"x-oanor-marketplace-url":"https://www.oanor.com/api/gemstone-api"}