Love / Polish Ring Sizes in US sizes? [2]

Hello,

I'll be going on vacation to Barcelona and Rome with my Polish girlfriend for our one year anniversary. I found out she wears a size 12 ring in Poland, but don't know what size to buy in US measurements (I live in Los Angeles). I was wondering if anyone had any good conversion charts or knew what equivalent size this would be in US or UK sizes so that I might find an appropriately sized (non-engagement) ring? I can only find UK, Swiss, or German sizes and charts. I'm not sure if Polish sizes fall into any of these categories.

Any help would be much appreciated.

Thanks in advanced.