The Ring Guide: Sizes, Metals, Settings, Hallmarks and Value
Everything that isn’t the stone: size, metal, setting, stamps and what a ring is worth.
Updated
The center stone gets the attention, but the ring around it decides whether it fits, how it wears, whether it can be resized and what anyone will pay for it later. These guides cover those decisions in the order you meet them.
Choosing a ring
Size, metal and setting — the decisions that are hardest to undo.
- How to Find Your Ring Size at Home Without Guessing A millimetre either way is most of a ring size. Learn how to measure properly, convert US to UK and EU sizes, handle a wide knuckle, and know which rings can never be resized.
- Ring Metals Compared: 14K, 18K, White Gold, Platinum Higher karat is not automatically softer, platinum is no longer the expensive metal, and white gold arrives with a maintenance bill. What each alloy actually does on a hand.
- Diamond Ring Settings Explained: Prong, Bezel, Halo & More The setting decides how big a diamond looks, how safely it sits, and what the ring costs. Compare prong, bezel, pavé, halo, and tension settings before you buy.
- Engagement Ring Cost: Where the Money Actually Goes A ring is nine decisions, and only three of them move the price much. Here is what each choice costs, why carat weight is the steepest lever, and how to buy visible size for less.
Identifying and valuing a ring
Read the stamps inside the band and turn them into a number you can act on.
- How to Identify a Ring: Hallmarks, Metals & Maker’s Marks Almost every ring carries an ID card inside the band. Learn to read 375, 585, 750, 925 and PT950, spot GF and GP plating marks, and tell solid gold from a shell.
- What Is My Ring Worth? The Four Numbers Nobody Explains One ring has four different values — melt, resale, insurance, and retail. Learn how each is calculated, run the gold math yourself, and know which number you need.
Tools for this topic
Ring Identifier: Jewelry AI Scan rings and jewelry to identify details and estimate value. 
Diamond identifier - AI Scan Scan diamonds to estimate quality and value with AI. Engagement Ring Designer Design a ring in 3D and watch an indicative price move with every choice. Diamond Size Chart Carat weight to millimetres for ten shapes, with a true-to-scale preview. Collector’s Glossary Plain-English definitions of the terms graders, dealers and auction houses use. The essentials
| Stamp | Metal | Purity |
|---|---|---|
| 375 / 9K | Gold | 37.5% |
| 417 / 10K | Gold | 41.7% |
| 585 / 14K | Gold | 58.5% |
| 750 / 18K | Gold | 75% |
| 925 | Sterling silver | 92.5% |
| 950 / PT950 | Platinum | 95% |
| GP, GF, HGE, RGP | Plated or filled | Not solid gold |
Frequently asked questions
How do I find my ring size at home?
Measure the inside diameter of a ring that already fits in millimetres and convert it; one full US size is about 0.81 mm of diameter or 2.55 mm of circumference. Size up half a size for wide bands.
Is platinum or white gold better?
Platinum stays white without plating and is hypoallergenic for most people; white gold is lighter and usually needs rhodium replating every one to two years.
What does 750 mean on a ring?
It is 75% pure gold — 18 karat.
How much is my gold ring worth?
Its melt value is weight in grams × purity × the current gold price per gram; specialist buyers typically pay 70–90% of that for plain gold.
Which rings can’t be resized?
Full eternity bands, tension settings and most titanium, tungsten and ceramic rings.
Sources and further reading
- 16 CFR Part 23 — Guides for the Jewelry, Precious Metals, and Pewter Industries — U.S. Electronic Code of Federal Regulations
- Hallmarking — The Goldsmiths’ Company Assay Office (London)
- Hallmarking Act 1973 — legislation.gov.uk
- Ring size — Wikipedia
Links checked September 14, 2026.