Plated items appearing in search when composition filter is set to "precious"

When the composition filter is set to “precious”, I'm having plated items appear.  That doesn't seem like it should be the intended behaviour?

To give an example, in this search: https://en.numista.com/catalogue/index.php?e=ancienne_urss&r=&st=147-150-149&cat=y&im1=&im2=&ru=&ie=&ca=3&no=&v=&a=&dg=&i=&b=&m=p&f=&t=&t2=&w=&mt=&u=&g=&c=&wi=&sw=

This item appears near the top of the results N#450245

It contains precious metal so the search functions as intended.

Idolenz

It contains precious metal so the search functions as intended.

I guess I can't fault your logic. 😄

I don't think that's how most users would expect it to work though.  I certainly wouldn't expect a search for gold coins to return gold plated coins, as technically correct as that is.

Perhaps there should be an option to only search the “core” material, or search fields could be added for core composition and plating composition?

related https://en.numista.com/forum/topic173612.html