In recent years, "new materials" have become widespread in the watch market. The use of unconventional materials for the exterior and movement of watches has brought about major changes not only in terms of design, such as shape and color, but also in performance. Issue 112 of Chronos Japan featured an article on these "new materials" titled "New Materials That Have Changed Watches," and this article is republished on webChronos. In this second installment, we will take a deeper look at 18K gold, which combines tradition with unique new recipes, using the examples of "18K King Gold" and "18K Magic Gold" developed by Hublot.
Photographs by Takeshi Hoshi (estrellas), Yu Mitamura
Hiroyuki Suzuki: Interview and text
Edited & Text by Hiroyuki Suzuki
[Article published in the July 2024 issue of Kronos Japan]
What is the new generation of 18K gold developed exclusively by Hublot?
Despite being the most familiar and traditional material in the Swiss watch industry, 18K gold continues to see new alloy recipes being developed. Hublot is one of the opinion leaders in the development of 18K gold compositions. Here, we will explore the material properties required for the new generation of 18K gold, using the "18K King Gold" and "18K Magic Gold" developed by Hublot as examples.
Hublot's proprietary "18K King Gold" and "18K Magic Gold"
This is the fourth case shape, released in 2022. It follows the concept and details of the Big Bang while featuring a refined square shape. Automatic winding (Cal. HUB1280). 43 jewels. 28,800 vph. Power reserve of approximately 72 hours. 18K King Gold and ceramic case (case diameter 42mm, thickness 14.7mm).
18K gold is the most common exterior material used in the watch industry. Its base, pure gold, is chemically stable and easy to work with, making it a popular choice for decorative items since ancient times. However, because it is too soft in its original form, 18K gold alloyed with other metals is now widely used. The gold content of the material is 75% by weight. This means that the remaining 25% of the alloy, made up of silver and copper, known as alloys, determines the color and properties of 18K gold.
Incidentally, ISO has regulations regarding alloy color, and 5N (red) refers to a silver content of 4.5-5.5% by weight. However, 5N 18K gold, which has a reddish color, contains a lot of copper, which is easily oxidized and sulfided, so the red color fades over time. A new gold alloy that meets this requirement is reddish 18K gold, which contains small amounts of rhodium or platinum.
The case and bezel are made of highly scratch-resistant Magic Gold. The technique of infiltrating pure gold into porous ceramic creates a unique texture. Automatic winding (Cal. HUB1280). 43 jewels. 28,800 vph. Power reserve approximately 72 hours. 18K Magic Gold case (diameter 44mm, thickness 14.5mm). Limited to 200 pieces worldwide.
18K King Gold, introduced in 2010 as Hublot's exclusive material, is one such platinum-containing red gold. Its reddish color is more vivid than the conventional 5N gold, and because platinum inhibits the oxidation and sulfidation of copper, it is also resistant to aging. What Hublot has achieved with 18K King Gold is the sustainability of beautiful colors.
On the other hand, while traditional 18K gold is hardened by alloys, it remains an overwhelmingly soft metal compared to other materials. While this issue has been addressed by applying a special hardening treatment to the surface, Hublot's "18K Magic Gold" is fundamentally different from other materials. This new material, developed through joint research with EPFL (Swiss Federal Institute of Technology in Lausanne), was announced in 2011. By replacing all alloys with ceramics, scratch-resistant gold has been achieved.
What's interesting about its manufacturing process is that, while all other new-generation golds are based on metallurgical techniques, 18K Magic Gold uses a method in which pure gold is infiltrated into a porous ceramic case. Unlike conventional ceramic case manufacturing, the case is molded into a cylindrical shape without a binder under high pressure and fired at the lowest possible temperature (mainly controlled by firing time) that prevents the boron carbide from fusing. The porous ceramic case ébauche, a small amount of aluminum, and pure gold are then sealed in a special container and fired under pressure, allowing the gold to flow into the ceramic's pores. The weight of the pure gold placed in the container is approximately three times the combined weight of the ceramic case and aluminum binder. This means that it is 75% pure gold by weight, earning it official recognition as 18K gold from the Swiss Precious Metals Office. Its distinctive features include a wet-like surface texture and a distinctive, bluish gold color. Because the raw materials are free of oxidation and sulfuration, it is a material that is resistant to aging.
