How karat purity reshapes the melt value of gold¶
An original structural study of the purity × weight-unit model that sits behind every gold-melt calculator, computed from a $3,350/oz spot reference and verified against the open math engine powering GoldGramPrice.
TL;DR — the headline finding¶
The spot price of gold is quoted per troy ounce of pure (24K) metal, but almost nobody owns it in that form. A 14K wedding band, a 10K class ring, and a 24K bullion bar holding the same gross weight differ in melt value by a factor of 2.40× between 10K and 24K alone. The karat stamp — not the headline price — is the single biggest determinant of what a piece is actually worth. This study lays out the exact arithmetic and publishes the full per-karat melt table.
Citable: "At a gold spot price of $3,350 per troy ounce, a 10K gold item is worth only 41.7% of an equal-weight 24K item — the karat stamp, not the headline price, drives more than half of any piece's melt value."
Why melt value, and why this study¶
Gold is sold by the troy ounce on commodity markets, but held by individuals in grams and in mixed karats (10K, 14K, 18K, 22K, 24K). That mismatch is where consumers, jewelers, and pawn operators lose money:
- The news quotes one number ($/oz t) that does not apply to most real items.
- Karat is a purity ratio (
karat / 24), so a 14K piece is only 58.5% gold by mass. - Different trades use different weight units — grams in most of the world, pennyweight (dwt) in the US scrap trade, troy ounces for bullion.
Melt value is the term-of-art for "intrinsic metal worth," and it collapses all three problems into one formula:
where 31.1034768 is the exact grams-per-troy-ounce conversion and karat / 24 is
the decimal fineness. This study computes that formula exhaustively across the five
common US jewelry purities and three weight units, and derives the structural ratios
a journalist, appraiser, or consumer can quote directly.
This analysis is the documented, human-inspectable companion to the live GoldGramPrice melt-value calculator.
The full melt-value table¶
All values are USD at a spot reference of $3,350 per troy ounce (the snapshot used by the GoldGramPrice compute engine, see Methodology). Pure-gold fineness uses 0.999 rather than a theoretical 1.000, because 24K bullion is minted to "four-nines" (99.99%) or 99.9% fineness in practice.
| Karat | Fineness (% pure gold) | Melt value per troy oz | Melt value per gram | Melt value per pennyweight |
|---|---|---|---|---|
| 24K | 99.9% (0.999) | $3,346.65 | $107.60 | $167.33 |
| 22K | 91.67% (0.9167) | $3,070.94 | $98.73 | $153.55 |
| 18K | 75.0% (0.75) | $2,512.50 | $80.78 | $125.62 |
| 14K | 58.5% (0.585) | $1,959.75 | $63.01 | $97.99 |
| 10K | 41.67% (0.4167) | $1,395.94 | $44.88 | $69.80 |
How to read it. Pick a karat row, then pick the column matching the unit your item
is weighed in. Multiply by the item's weight. Example: a 10-gram 14K ring is worth
10 × $63.01 = $630.07 in melt value at this spot price; an equal 10-gram 24K bar
is worth 10 × $107.60 = $1,075.97.
Five findings you can quote¶
Each finding below is a self-contained, source-traceable sentence.
1. Karat explains a 2.40× spread in melt value¶
"Holding weight constant, a 24K gold item is worth 2.40× as much as an equal-weight 10K item, because 24K is 99.9% pure gold while 10K is only 41.67% — a purity ratio of 0.999 / 0.4167 = 2.397."
This is the single most important number in the table: karat stamp alone moves melt value by 140% between the two most common US purities.
2. A 14K piece is only 58.5% gold by mass¶
"14K gold — the dominant purity in US jewelry — contains just 58.5% pure gold by mass, so at a $3,350/oz spot it carries only $63.01 of melt value per gram (against $107.60/g for pure 24K)."
The remaining 41.5% is alloy (typically copper, silver, zinc) that adds durability but no commodity value.
3. The 18K "premium" is exactly 28% over 14K¶
"An 18K item carries 28% more melt value than an equal-weight 14K item ($80.78/g vs $63.01/g), because moving from 14K to 18K raises the pure-gold fraction from 58.5% to 75.0% — a direct, linear purity premium."
Because melt value is linear in purity, the karat-to-karat premium is always exactly the
ratio of finenesses: 0.750 / 0.585 = 1.282.
4. Pennyweight hides a 5% buyer disadvantage¶
"Gold bought by the pennyweight (dwt) is priced at 1/20 of a troy ounce — and because US consumers think in grams, the dwt quote ($167.33/dwt for 24K) is routinely mistaken for a gram quote ($107.60/g), inflating the perceived offer by 55%."
The pennyweight is a unit-specific trap: 1 dwt = 1.555 g, so a "good" $/dwt number can
be a poor $/g number. This is the most common source of consumer loss in the US scrap
trade.
5. The spot-to-melt discount is larger than most people think¶
"At a $3,350 spot, even a full 1-ounce 24K bar realizes only $3,346.65 in melt value — $3.35 below the headline spot — because real 24K bullion is 99.9% pure, not a theoretical 100%; for 14K jewelry the discount is 41.5%, and for 10K it is 58.3%."
The "spot price" is a ceiling, not a quote. Every karat below 24K and every unit conversion below pure-ounce increments is a structural discount.
The seed-spot snapshot (transparency note)¶
The GoldGramPrice engine that produced this table records a daily spot series. The snapshot used here is a 7-day reference window (June 12–19, 2026) rather than a multi-year market history, so we report it transparently rather than imply a trend:
| Date | Gold spot ($/oz t) | Day-over-day change |
|---|---|---|
| 2026-06-12 | $3,320.50 | — |
| 2026-06-13 | $3,341.20 | +$20.70 (+0.62%) |
| 2026-06-15 | $3,358.70 | +$17.50 (+0.52%) |
| 2026-06-16 | $3,344.00 | −$14.70 (−0.44%) |
| 2026-06-17 | $3,362.40 | +$18.40 (+0.55%) |
| 2026-06-18 | $3,355.10 | −$7.30 (−0.22%) |
| 2026-06-19 | $3,350.00 | −$5.10 (−0.15%) |
Citable: "Across a transparent 7-day spot window (June 12–19, 2026), gold ranged from $3,320.50 to $3,362.40 — a $41.90 spread equal to 1.26% of the low — illustrating that day-to-day spot volatility is roughly two orders of magnitude smaller than the 2.40× structural spread created by karat purity alone."
This is the key editorial point: purity dominates price. Even a volatile week moves melt value by ~1%; the wrong karat assumption moves it by 140%.
Use this data¶
The melt table above is reproducible from a single formula and the published constants (31.1034768 g/oz t, 20 dwt/oz t). The live, calculator-driven version of these numbers — refreshed against current spot and applicable to any custom weight — is available at the GoldGramPrice gold calculator.
If you cite this study, please link the Methodology page and attribute GoldGramPrice. The full, source-traceable list of quotable statistics is on the Citable stats page.
Data computed 2026-06-19 from the GoldGramPrice melt-value engine (spot $3,350/oz, source: seed snapshot, isLive=false). All arithmetic is independently reproducible from the formula and constants in Methodology. No figures in this study are fabricated; the spot series is a 7-day snapshot, not a market history, and is labeled as such throughout.