What metal is used to cast the Nobel prize?
Executive summary
The Nobel Prize medals awarded today are cast in 18‑carat "green gold" (an alloy of gold and silver) and since 1980 have been plated with 24‑carat gold; earlier medals were made of higher‑carat solid gold (traditionally 23‑carat) [1] [2] [3]. Major reference authorities — the Nobel Foundation and reputable press and reference sources — describe the contemporary medal as 18K gold (often recycled) with a 24K surface finish, while historical medals used 23K gold [4] [5] [6] [7].
1. What "metal" means for the Nobel medal: alloy, not pure gold
The modern Nobel medal is not solid 24‑carat gold but an 18‑carat alloy commonly called green gold — a mixture of gold and silver — which is then plated with pure (24‑carat) gold to give the bright finish associated with the prize [1] [5]. Official Nobel information and secondary reporting emphasize that the visible surface is pure gold plating, while the bulk of the medal is an 18K alloy rather than 24K bullion [5] [1].
2. A change in composition: 23K to 18K around 1980
Historical practice is different: medals made before 1980 were struck in 23‑carat gold, whereas medals minted since about 1980 have been produced in 18‑carat gold and plated with 24‑carat gold [2] [1] [3]. Several sources — including the Nobel organizations’ materials about the Peace medal and independent explainers — record that the Peace medal originally weighed about 192 grams of 23‑carat gold but from 1980 onward was changed to 18‑carat at roughly 196 grams [2] [8].
3. Official sources and reputable press converge on the current metal description
The Nobel Foundation’s public descriptions and the Nobel Prize site characterize the medals as gold, and contemporary reporting has specified “18‑karat recycled gold” in recent years, reflecting both the 18K alloy and environmentally framed sourcing practices now used by the foundation [5] [6]. Encyclopedic and museum sources echo that formulation, with Britannica noting 18‑carat recycled gold and the Nobel Prize site and Peace Prize center providing the 18K/24K distinction and the historical 23K note [7] [5] [8].
4. What "green gold" is — and limits in the reporting
Explanatory pieces identify green gold as an alloy of gold and silver that yields a slightly different hue than yellow gold; this label helps explain why the medal is plated with 24‑carat gold to achieve the expected appearance [1]. Sources consulted do not, however, publish a precise alloy formula (percentages of gold vs. silver or other trace metals) for the 18K green gold used in modern medals, and official statements emphasize carat and plating rather than detailed metallurgical recipes [1] [5].
5. Why the change matters: durability, cost and provenance
The shift from 23K solid gold to 18K alloy plated with 24K likely reflects practical choices — 18K alloys are harder and more durable than higher‑carat soft gold, and modern procurement practices have emphasized recycled gold — a point highlighted by the Nobel Committee and reporting on medal auctions and provenance [2] [6]. Auction reporting noting medals sold for millions reiterates that their monetary and historic value far exceed their metal bullion worth, but those reports also restate the 18K recycled gold characterization for post‑1980 medals [6].
6. Bottom line and sources of authoritative nuance
In plain terms, Nobel medals awarded since about 1980 are cast in 18‑carat green gold and finished with 24‑carat gold plating; medals prior to that date were made in 23‑carat gold [1] [2] [3]. The Nobel Foundation, NobelPrize.org, national prize‑site materials and major press and reference outlets (NobelPrize.org, Nobel Peace Center, Britannica, New York Times and technical explainers) form the evidentiary basis for this conclusion, while exact alloy recipes and sourcing details (beyond “recycled” statements used in some recent coverage) are not published in the materials reviewed here [5] [8] [7] [6] [1].