Mix of Yellow and White Gold? Like H. Stern''s Noble Gold?

[jgny]

Does anyone know of companies (or even an etsy vendor) that offers items in a mix of yellow and white gold? I love the pieces from H. Stern that are made of noble gold, but was looking to commission some pieces using a similar mix - I love that it matches with both silver and gold pieces:

From H Stern''s site:

Noble Gold
More than two years of studies and more than 180 metallic combinations were necessary to reach the perfect result. The silver tone launched by H.Stern has the heat of the yellow gold and the refinement of the white gold. It causes sensation! The alloy and the proportions of each metal of the mixture are "H. Stern secret". The combination of the noble gold color, reminding a family jewel, and the modern design gives the pieces a very contemporary aspect. Noble gold jewels are perfect to be worn with other pieces made of different colors of gold, creating a sophisticated and modern effect.

An example of a piece in noble gold

 

[jgny]

A ring in noble gold:

 

[Lady_Disdain]

Alloying is quite a field for research. There are countless recipes for alloys, from the japanese shibuichi (which has a lot of variations all by itself) to high carat alloys. Most "traditional" recipes use silver, copper and gold, but modern metallurgy has combined many other metals (such as germanium for argentum silver or aluminum for coloured gold). There are specialists turning out gorgeous materials with interesting specifications (for example, Kretchner developed alloys that allowed tension setting to be much slimmer and more streamlined).

While small workshop artisans can alloy their own metals, many modern recipes need very specialized equipment (either because of temperature or controlled atmosphere, etc). In HStern''s case, I am pretty sure there are some unusual metals in the mix (I talked about this for a while with one of their better salespeople). I am also very puzzled by their comparison to white metal, as the colour of noble gold is more of a brownish cognac colour and not white at all!