Identify gold and understand purity (karat & hallmarks)
Track: Jewelry Making & Goldsmithing Β· Duration: 28 min
Video lesson
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Course reader
Identify gold and understand purity (karat & hallmarks)
Scribd-style reading pane β scroll the page like a classroom workbook next to the video.
Karat and purity
- 24k β 99.9% fine gold (very soft for most jewelry).
- 18k = 75% gold by weight; 14k β 58.3%; 10k β 41.7% (US minimum for βgoldβ jewelry varies by law).
- Hallmarks / stamps may show karat or millesimal fineness (e.g. 750 = 18k).
Practical identification
- Visual: color hints (alloys), wear patterns, solder seams.
- Magnet: strong attraction suggests not pure gold (often steel core / plating β not definitive alone).
- Density / displacement (careful methodology) can support ID for homogeneous pieces.
- Acid test kits (scratch stone): common in trade; follow kit instructions; acid is hazardous.
- XRF gun / lab assay: best for unknown alloys and legal compliance when buying scrap.
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Lesson quiz
Each attempt uses a random set of questions with shuffled answer choices. Pass at 70% or higher to mark the lesson complete.