**STUDIO GUIDELINE 03**

# Metal Purity & Marking

*Origin is one claim. Fineness is another. A stamp is a third.*

Do not stamp 925, 14K, or any quality mark unless the finished alloy meets that floor. Mixed melts are unmarked until the number is known.

## Gold
Purity percent = (karat / 24) x 100.

- 999 / 24K ~99.9% — bullion
- 916 / 22K ~91.7%
- 750 / 18K 75%
- 585 / 14K ~58.3%
- 417 / 10K ~41.7%
- 375 / 9K 37.5% — Canadian floor for a gold quality mark

## Silver
- Sterling: 925
- Britannia: 958
- Fine: 999 — do not stamp sterling

## Copper
Not a precious metal under the Precious Metals Marking Act. Recycled copper wire is a source claim only.

## Canada
A quality mark is optional. If applied it must be true. Canada expects a trademark with the mark unless hallmarked under another country's rules.

## Three public lines
1. Handmade; metal may be mixed origin; not quality-stamped.
2. Handmade; this batch assayed or calculated at [number] and stamped [number].
3. Sterling 925 — purchased stock only, kept off the field melt.