Weight, Diameter & Specific Gravity Testing
March 9, 2026
Your First Line of Defense
Genuine US coins have precise specifications. Counterfeiters often get weight wrong — determined by metal composition. A digital scale ($15–$25) accurate to 0.01g is essential.
Standard Weights
- Lincoln cent (copper) — 3.11g | Lincoln cent (zinc) — 2.50g
- Nickel — 5.00g | Dime (silver) — 2.50g | Dime (clad) — 2.27g
- Quarter (silver) — 6.25g | Quarter (clad) — 5.67g
- Half dollar (silver) — 12.50g | Half dollar (clad) — 11.34g
- Morgan/Peace dollar — 26.73g | Silver Eagle — 31.10g
- $20 gold — 33.44g | $10 gold — 16.72g | $5 gold — 8.36g
Coins off by more than 0.20g are suspicious.
Diameter Testing
Digital calipers ($10–$20) measure to 0.01mm. Even 0.5mm off is a red flag.
Specific Gravity
Measures density relative to water. Nearly impossible to fake both correct weight AND correct specific gravity with the wrong metal.
- 90% silver — 10.34 | 22K gold — 17.15–17.75 | Copper-nickel clad — 8.92
Method: Weigh dry, weigh suspended in water, calculate SG = dry ÷ (dry − wet).
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This article is for educational guidance. Where official grading rules, dealer memberships, legal requirements, or tax obligations apply, consult the relevant primary authority.
Last reviewed January 28, 2026 by the US Coin Shows editorial team. Editorial policy
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