Learn English – “Strike gold” but without the implication of searching

It's often been said that beauty is in the eye of the beholder. What one person finds trashy, slutty, tarty, cheap or tacky-looking in a woman; another sees a woman who oozes self-confidence, style, glamour and sex-appeal.

A woman who has put on a gaudy outfit could be described as being dressed to the nines; gussied, fancied or dolled up; sassy; and looking to have fun. If she is dressed provocatively (gaudy outfits), wears expensive cosmetics (garish makeup), and prefers costume jewelry (excessive jewelry) to that of gold and platinum, she is said to be dressed to kill.

She can be called a man-eater; a seductress; a flirt; a femme fatale or just a socialite

Socialite
She lives in a paradise of a mansion, usually in California, or a penthouse in Manhattan. You might find her hanging out at various social events, with a glass of champagne in her hand. Often she doesn't have a job, but sometimes she can be working in a high-end job, such as that of a celebrity publicist, which nets her a very high salary. (...) Can also be prone to Conspicuous Consumption, especially jewels, fancy dresses, and furs.

Alternatively, if she is young and has recently come into money she might be termed as

Nouveau Riche
The Nouveau Riche are characterized as rude and tasteless, and frequently contrasted with the refined manners of aristocratic Old Money characters. (...) If American, expect them to be Hollywood California people with bleach-blonde Valley Girl daughters, slovenly white trash who won either the lottery or a big-time settlement ... If black, expect a flashy character from a Glam Rap video. (...) Common accessories for this class include fur coats, gaudy jewelry, obnoxiously color-coordinated suits, and gold teeth.

Source: TV Tropes

I disagree that the variant "You're one of the most beautiful women I've ever seen" is profoundly less romantic than the original. It's honesty is actually refreshing when compared with the very cliche original sentence, which might actually make the variant more romantic.

Further, this rephrasing seems to be precisely what you need to accommodate the truth of the situation, since truth seems to be important to you.

If there's any left-over sentiment that you need to capture, you might add a conjunction: "You're one of the most beautiful women I've ever seen and...".

Or, you could drop the quantifiers entirely and just go with "You're [insert poetic adverb] beautiful." For example, "You're howl-inducingly beautiful."