My long-ago ex-girlfriend would have been nasty enough (she was engaged to a guy before she met me) to tell you to your face that she was going to sell it if she didn't like it. As it was, she got rid of a ring watch that she wanted that I bought for her but bought one pretty much like it.
If I ever met a woman I wanted to marry, I would think want to know her favourite colour and if it was blue, buy her a sapphire, if red, a ruby, etc. The thing is, though, if I asked her to marry me, I wouldn't get down on bended knee in a restaurant or park, I would give her three small pieces of paper with clues, such as, "Sounds like a female sheep," (the answer she'd need is, "Ewe," Ewe-You), and have others leading her to a book. Then she'd have clues such as, "Page 29, Line 5, Word 6, Showa Emperor rebukes Seishiro Itagaki), the word she'd need was "Will." She'd then use the next clues to find, "you marry me?"
The type of woman I would want would not be overly materialistic, and the ring would mean little to her.