Generally, on solid gold Swiss made Omega cases there should be a small hallmark behind one of the lugs. Here is an example:
See the lower left lug in the above photograph. You can't see it here, but 18K gold will have a very tiny Queen's head and 14K gold will have a squirrel inside the hallmark.
Given the slight decline in the price of gold recently, the price is somewhat high and I'm not crazy about the country of origin, but it does meet your critieria.
http://www.ebay.com/itm/VINTAGE-OME...925764154?pt=Wristwatches&hash=item1c27bcba3aPurchases made through these links may earn this site a commission from the eBay Partner Network
Take care,
gatorcpa
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