Troy オンス: Measuring Precious Metals
The Weight System Behind Gold and Silver
Try 重量コンバーターWhen you see gold prices quoted at "$2,000 per ounce," that's not the same ounce you'd use to measure flour. Precious metals use a different system called troy weight, with the troy ounce as its primary unit. 理解する this distinction is essential for anyone buying, selling, or investing in gold, silver, platinum, or palladium.
の歴史 the Troy System
The troy weight system takes its name from Troyes, a French city that hosted major medieval trade fairs. In the Middle Ages, Troyes was a commercial hub where merchants from across Europe traded precious metals, gems, and other valuable goods.
The troy system became the standard for precious metals because:
- It was already established at major trading centers
- Its consistency helped prevent fraud in high-value transactions
- Precious metal dealers worldwide adopted it for standardization
変換先day, every major gold and silver market—London, New York, Shanghai—uses troy ounces.
Troy Weight Units
| Unit | グラム | Troy オンス |
|---|---|---|
| 1 grain | 0.0648 g | 1/480 oz t |
| 1 pennyweight (dwt) | 1.555 g | 1/20 oz t |
| 1 troy ounce (oz t) | 31.1035 g | 1 oz t |
| 1 troy pound | 373.24 g | 12 oz t |
Note: Unlike the avoirdupois system (16 oz per pound), the troy system has only 12 troy ounces per troy pound. This makes the troy pound actually lighter than the avoirdupois pound (373g vs 454g), even though the troy ounce is heavier.
Why Precious Metals Use Troy オンス
Historical Standardization
The troy system predates the avoirdupois system and was already established for precious metals when avoirdupois became common for other goods.
Precision
Precious metals require precise measurements due to their high value per unit weight. The troy system's pennyweight (1/20 oz) and grain (1/480 oz) provide fine gradations.
Global Consistency
Using a unique system ensures no confusion with regular ounces. When someone says "one ounce of gold," there's no ambiguity—it's always troy.
Precious Metal Products by Weight
| Product | Troy オンス | グラム |
|---|---|---|
| Gold American Eagle coin | 1 oz t | 31.1 g |
| Gold Krugerrand | 1 oz t | 31.1 g |
| Silver American Eagle coin | 1 oz t | 31.1 g |
| Good Delivery gold bar | ~400 oz t | ~12.4 kg |
| Good Delivery silver bar | ~1000 oz t | ~31.1 kg |
| Standard gold kilobar | 32.15 oz t | 1000 g |
よくある間違い
Confusing Troy and Regular オンス
If you buy "10 ounces" of gold expecting 283 grams and receive 311 grams, you got troy ounces (correct). But if someone tries to sell you gold at regular-ounce weights, you'd be cheated out of 10% of your purchase.
Troy Pound Confusion
A troy pound (12 troy ounces = 373g) is lighter than an avoirdupois pound (16 ounces = 454g). The ounce is heavier, but the pound is lighter!
Jewelry vs Bullion
Jewelry weight is often given in grams or pennyweights, while bullion uses troy ounces. Know which system applies to your transaction.
Troy オンス in Investing
理解する troy ounces is essential for:
- Spot prices: Gold and silver spot prices are always per troy ounce
- Futures contracts: COMEX gold contracts are 100 troy ounces; silver contracts are 5,000 troy ounces
- ETFs: Gold ETFs hold physical gold measured in troy ounces
- Coin collecting: Bullion coins are denominated in troy ounces
まとめ
The troy ounce has measured precious metals for over 500 years and remains the global standard today. At 31.1 grams, it's about 10% heavier than the regular ounce—a crucial difference when dealing with materials worth thousands of dollars per ounce.
Whether you're buying a gold coin, investing in silver bars, or simply following precious metal prices in the news, understanding troy ounces ensures you're speaking the same language as the global metals market.