Yellow gold and red gold coin weight difference

Is a weight difference between a yellow gold coin and red gold coin? Of course same coin just a variation of material. 

For example

100 Lire Victor Emmanuel III 1903 - Has a yellow gold version and a red gold version, but there is only one weight in the info pannel. Do you think there is a weight difference between this two variations?

thanks for helping 

I suppose that depends on if the coins are made of the same carat of gold to start with. 

The coin you linked to is 21ct yellow gold which must be 87.5% gold and the additives are the rest 12.5% nickel, copper sometimes silver, rose gold 21ct would have to be 87.5% gold and 12.5% additive copper and whatever else.

Logic says an ounce of rose gold is the same as an ounce of yellow gold and an ounce is an ounce be it made up of feathers or sand its still an ounce. To be 21ct it has to contain the 87.5% gold either way to be yellow or rose. 

21ct rose gold and 21ct yellow gold are the same value gold wise per weight.

No.

According to the KM catalog, the coin is specified at 32.258 grams and 90% pure.

That means the comosition is 29.032 grams gold and 3.2258 grams of other metals regardless of what those other metals are.

As an aside, KM does not mention varieties of different color/alloy. 

It unusual to have a “red” gold at .900.  Typically red gold is limited to .750 (18k).

I couldn't fine any reference to this coin in two different alloys.

Yes, and given the era, they could not have dropped the fineness and still have a 100 Lire coin.

I saw one auction listing that refers to red gold, but with no further comments, and the color does not look especially “red” or pink, but gold coins can look different depending on lighting, etc.   https://www.acsearch.info/search.html?id=950988

It's very strange to look in acsearch and see so many sales of a coin with a mintage of only 966.

Yes, and speaking of a mintage of 966 (1,012 for 1905) it's very unlikely they made planchets with two different alloys.  

Thanks a lot for taking the time to reply. This is very useful. I have a 100 Lire 1903 coin, tested and its gold, the size is right, but the weight is not 32g. I don’t know what should I do. Can’t find to many details online about this coin, especially about the difference between the red and yellow version. 
 

There are reproductions:  https://www.coinarchives.com/w/lotviewer.php?LotID=6640150&AucID=7694&Lot=833&Val=a383e75e3a584cf8b5561040df6668b8

Authentic examples sell for 10,000 - 20,000 euro depending on grade.

@karrlot  If you have a suitable reference, can you please check if this type really exists in two different alloys?  

If we cannot verify this, we can combine the two date lines.  

rsirian1

It unusual to have a “red” gold at .900.  Typically red gold is limited to .750 (18k).

I couldn't fine any reference to this coin in two different alloys.

O I love that chart!