The floor: what the metal is worth
Three numbers, and you can do it on a phone:
- Weight in grams. Use a scale that reads to at least two decimal places. Jewellery scales are fine; kitchen scales are not.
- Purity as a decimal. Natural nuggets run roughly 70–95% gold. Without a test, 85% is a reasonable middle assumption — but it is an assumption, and it is the number most likely to be wrong.
- Gold price per gram. At $4,407 per troy ounce, pure gold runs about $142 per gram — and about $120 per gram at 85% fineness.
Multiply the three and you have the metal value. That is the number a scrap buyer works from, and for a nugget with any character it is the wrong answer — it is the starting point.
The premium: what makes the difference
Everything above the floor comes from how the piece looks:
- Size. The premium climbs steeply with weight, because large natural pieces are exponentially rarer than small ones. A single 10-gram nugget is worth considerably more than ten 1-gram nuggets.
- Shape and character. Distinctive outlines, crystalline structure and interesting texture all add value. Smooth, featureless lumps command less.
- Quartz. Gold still attached to its host rock is often worth more than the gold alone, despite weighing more and containing less metal. Specimen buyers want the contrast.
- Provenance. A documented creek or district adds value, particularly for famous ground.
Which is why standout pieces get quoted one at a time rather than off a rate table. Anything above roughly 5 grams, or with real character at any size, is assessed individually.
What not to do before you get it valued
Do not polish, tumble, or acid-clean a nugget. Natural surface is part of the product, and restoring it is impossible. Rinse off loose dirt, dry it, and leave it alone.