Ky, Kpw

One more time I resort to this website as the only reliable and accessible fountain of knowledge.

I'm trying to buy a gift from a very famous online jewelry store, they sent me a catalogue but all the pieces on it come in two different versions, ky and kpw.

For example, there's this ring that I like and I'm thinking about ordering it but I don't know which one to choose; the one that says 18ky or the one that says 18kpw.

I searched everywhere trying to find the meaning of these acronymos but my effort were in vain.

Does anybody knows what they stand for?
Help, please

I am not fully sure about these acronymos. But below are the references for your help.

http://www.e-goldprospecting.com/html/what_is_a_karat.html
http://www.furthers.com/damascus-rings.htm

18karat yellow gold (18 ky)

18karat palladium white gold (18 kpw)

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What is a KARAT
Gold Quality: Gold's purity is measured in karats. The term "karat" harks back to the ancient bazaars where "carob" beans were used to weigh precious metals. 24 karat is pure gold, but its purity means it is more expensive and less durable than gold that is alloyed with other metals. Different alloys are used in jewelry for greater strength, durability and color range.