Mystery Vintage brooch marked “sterling”

This pretty little pin is approx 2 ” tall and in excellent vintage condition. The 5 flower petals and single leaf look like carved mother of pearl, (but that’s just a guess). I found it at a church rummage sale on the junk/costume jewelry table in the pin & brooch section. Noting it’s appealing design and the fact that it was ‘marked’ I brought it home with me. I’ve used my jeweler’s loop to check out the marking but nothing about it is farmiliar to me. The tiny circular stamp has some type of maker’s symbol in the center with what looks to be three words that encircle it. The two words I can accurately identify are “STERLING” and “TREASURE” but I have no idea what the third word might be. I have tried to take the best pics I can of the tiny little mark and posted them here with pictures of the brooch hoping someone might be familiar with the symbol or company name and of corse I hope this will help me accurately date the piece as well. Since it is marked ‘sterling’ vs. ‘.925’ I’m guessing it pre-dates the 1970s but that’s the best I can do on my own. Thanks so much for having a look and sharing anything you might know or speculate about this piece!