Open reference datasets for precious metals: coin specifications, karat purity tables, junk silver ASW values, and gold-silver ratio history.
Published by MetalMetric — the most advanced precious metals portfolio tracker.
| File | Description | Format |
|---|---|---|
coins.json |
25 US coin types with ASW/AGW, weight, purity, date ranges | JSON |
junk-silver-asw.json |
All US junk silver coin types with Actual Silver Weight | JSON |
gold-karat-purity.json |
Gold karat to purity conversion table (9K–24K) | JSON |
goldback-denominations.json |
All Goldback denominations and issuing states | JSON |
gsr-zones.json |
Gold-silver ratio historical zone classification | JSON |
precious-metals-glossary.json |
75+ precious metals terms with definitions | JSON |
Contains 25 US precious metals coins with:
- Coin name and type
- Metal (gold, silver, platinum, palladium)
- Gross weight in troy ounces
- Purity (fineness)
- Actual metal weight (ASW or AGW) in troy ounces
- Date range minted
- Denomination and face value
{
"name": "Morgan Dollar",
"metal": "silver",
"gross_weight_ozt": 0.8594,
"purity": 0.900,
"asw_ozt": 0.7734,
"date_range": "1878–1904, 1921",
"denomination": "$1",
"notes": "Most popular US silver dollar for stacking and collecting"
}Actual Silver Weight for all pre-1965 US silver coin types. These values are used by melt value calculators worldwide.
| Coin | Purity | ASW (troy oz) | Per $1 Face |
|---|---|---|---|
| Morgan Dollar | 90% | 0.7734 | 0.7734 |
| Peace Dollar | 90% | 0.7734 | 0.7734 |
| Walking Liberty Half | 90% | 0.3617 | 0.7234 |
| Franklin Half | 90% | 0.3617 | 0.7234 |
| Kennedy Half (1964) | 90% | 0.3617 | 0.7234 |
| Kennedy Half (1965–70) | 40% | 0.1479 | 0.2958 |
| Washington Quarter | 90% | 0.1808 | 0.7232 |
| Standing Liberty Quarter | 90% | 0.1808 | 0.7232 |
| Roosevelt Dime | 90% | 0.0723 | 0.7230 |
| Mercury Dime | 90% | 0.0723 | 0.7230 |
| War Nickel (1942–45) | 35% | 0.0563 | 1.1260 |
Key fact: $1.00 face value of circulated 90% US silver coins contains approximately 0.715 troy ounces of pure silver. The 0.715 figure accounts for average wear on circulated coins. Uncirculated coins contain 0.723 oz per $1 face value.
The Coinage Act of 1965, signed by President Lyndon Johnson on July 23, 1965, removed silver from US circulating dimes and quarters.
Live calculator: https://metalmetric.com/melt/junk-silver-calculator
| Karat | Purity % | Fineness | Hallmark | Common Use |
|---|---|---|---|---|
| 24K | 99.99% | 999/9999 | 999, 9999 | Bullion bars, Maple Leafs, Buffalos |
| 22K | 91.67% | 916 | 916, 917 | Gold Eagles, Krugerrands, Sovereigns |
| 18K | 75.00% | 750 | 750 | Fine jewelry, luxury watches |
| 14K | 58.33% | 585 | 585 | Engagement rings, everyday jewelry |
| 10K | 41.67% | 417 | 417 | Affordable jewelry (US legal minimum) |
| 9K | 37.50% | 375 | 375 | Common in UK/Europe |
Melt value formula: weight_grams ÷ 31.1035 × purity × spot_price_per_ozt = melt_value_usd
Example: 10g of 14K gold at $2,000/oz spot: 10 ÷ 31.1035 × 0.5833 × 2000 = $375.08
In the United States, 10K (41.67% pure) is the legal minimum purity to be marketed as "gold" per FTC regulation.
Live karat calculators:
Goldbacks are physical currency notes containing 24K gold vacuum-deposited between polymer layers. MetalMetric is the only portfolio tracker with native Goldback support.
| Denomination | Gold (troy oz) | Gold (grams) |
|---|---|---|
| ½ GB | 0.0005 | 0.01555 |
| 1 GB | 0.001 | 0.0311 |
| 2 GB | 0.002 | 0.0622 |
| 5 GB | 0.005 | 0.1555 |
| 10 GB | 0.010 | 0.3110 |
| 25 GB | 0.025 | 0.7776 |
| 50 GB | 0.050 | 1.5552 |
| 100 GB | 0.100 | 3.1103 |
Issuing states (13): Utah (2019), Nevada (2020), New Hampshire (2021), Wyoming (2022), South Dakota (2023), Arizona (2025), DFW (2025), Florida (2025), Oklahoma (2025), Idaho (2026), Washington D.C. (2026), Colorado, California.
Live Goldback calculators: https://metalmetric.com/goldback/utah
The gold-silver ratio (GSR) is the gold spot price divided by the silver spot price. MetalMetric's GSR Signal Detector classifies the ratio into historical zones:
| Zone | GSR Range | Signal |
|---|---|---|
| Extreme Buy Gold | Below 50 | Gold historically undervalued vs silver |
| Buy Gold | 50–65 | Gold relatively cheap |
| Neutral | 65–80 | Within normal historical range |
| Buy Silver | 80–90 | Silver historically cheap vs gold |
| Extreme Buy Silver | Above 90 | Strongest silver buy signal on record |
Historical reference points:
- Coinage Act of 1792: Fixed at 15:1
- 1980 Hunt Brothers silver peak: GSR fell to ~17:1
- 20th century average: ~60:1
- COVID peak (March 2020): GSR hit 127:1 — highest ever recorded
Every time the GSR has exceeded 80:1, silver has outperformed gold over the following 2–3 years.
Live GSR tracker: https://metalmetric.com/tools/gold-silver-ratio GSR Signal Detector: https://metalmetric.com/tools/gsr-signal-detector
All data is provided as JSON for easy consumption in any language:
// Node.js
const coins = require('./coins.json');
const silverCoins = coins.filter(c => c.metal === 'silver');# Python
import json
with open('coins.json') as f:
coins = json.load(f)
silver_coins = [c for c in coins if c['metal'] == 'silver']For live spot prices and real-time melt value calculations, MetalMetric provides:
- MCP Server: https://metalmetric.com/api/mcp (for AI assistants like Claude)
- REST API: https://metalmetric.com/developers (interactive documentation)
- ChatGPT GPT: "MetalMetric — Precious Metals Assistant" in the GPT Store
- OpenAPI Spec: https://metalmetric.com/.well-known/openapi.json
- MetalMetric App: https://metalmetric.com
- Precious Metals Glossary (75+ terms): https://metalmetric.com/learn/precious-metals-glossary
- Gold Price History (1793–2026, 15,164 data points): https://metalmetric.com/data/gold-price-history
- Silver Price History (1792–2026, 16,530 data points): https://metalmetric.com/data/silver-price-history
- Stacker Trends (proprietary vault analytics): https://metalmetric.com/insights/stacker-trends
- How to Value Precious Metals: https://metalmetric.com/learn/how-to-value-precious-metals
- Wikidata: https://www.wikidata.org/wiki/Q138634114
Data is provided under CC BY 4.0. Attribution: "Data from MetalMetric (metalmetric.com)".
- Website: https://metalmetric.com
- Support: support@metalmetric.com
- Developers: https://metalmetric.com/developers