Gold Filled / Gold Double
Also: double, gold filled, rolled gold, doublé
Gold double is a base-metal core (usually brass or copper) that is mechanically bonded to a thick layer of gold by hot rolling — as opposed to electroplated gold plating.
Gold double (also doublé, or in English gold filled or rolled gold) describes a composite material in which a relatively thick layer of gold is permanently bonded to a base carrier — usually brass, copper or nickel silver — by mechanical hot rolling or pressing. The result is visually almost indistinguishable from solid gold, yet contains only a fraction of the gold value.
Manufacture and construction
In the double process a sheet of gold (usually a 333 to 750 alloy) is rolled together with the base metal at high temperature until the two layers form an inseparable metallic bond. The gold layer makes up at least 1/20 of the total weight (the American gold filled standard) and, at 20–100 micrometres, is far thicker than an electroplated gold plating (0.1–5 µm). This layer thickness gives gold double considerably better wear resistance.
Distinguishing double, plating and doublé
| Feature | Gold double | Electroplated gold plating | Solid gold |
|---|---|---|---|
| Bond | Mechanical (rolling) | Electrolytic | Monolithic |
| Layer thickness | 20–100 µm | 0.1–5 µm | Solid material |
| Gold share of weight | approx. 5% | < 0.1% | 100% |
| Durability | High (years to decades) | Low to medium | Permanent |
| Overall fineness | Below 333 ‰ | Below 333 ‰ | Depends on alloy |
Important: because the fineness of the whole item is generally below 333 per mille, gold double is not classed as a precious metal under precious-metal law and may not be stamped with a hallmark for genuine gold.
Marking and legal position
In Ireland and across the EU, gold double must be clearly identified as such — typical markings are GF (gold filled), RG (rolled gold), Doublé or a designation such as 20/1000 GF 14K. A misleading description as "gold" or a genuine gold hallmark is prohibited. In the United States the FTC Jewelry Guides set the minimum requirements for gold filled jewellery.
You can estimate the actual material value with the melt value calculator — though for double items only the weight of the gold layer is relevant, not the total weight. Whether a piece is really double or in fact solid gold is revealed by the authenticity check or a professional streak/acid test at a jeweller.
Formulas for the gold share
Gold weight = total weight × (layer share / 1000) × (fineness carat / 24)
Example: 10 g bracelet, 1/20 GF, 14K → 10 × 0.05 × 0.583 ≈ 0.29 g fine gold
In brief
Gold double offers the visual shine of gold at a fraction of the price, but holds no meaningful material value as a precious metal. For purchase and melting, the actual fine-gold content is decisive — this can be worked out with the purchase-price calculator once the layer parameters are known.