Gold tone tree brooch w/ multicolor rhinestones marked “STER. PO”?

I have been trying to figure out who made this brooch and approximately when it woul have been manufactured. It DOES strongly resemble a Sarah Coventry brooch I’ve found online w/ two small differences; the # of rhinestones, ( mine has 8 and the Sarah Coventry has 11), as well as the SarahCov mark). Also, almost the exact same pin was made by the Vintage Curtis Jewelry Company and was called the “Sterling Silver Tree of Life” and is stamped “STERLING” with the company’s maker’s mark - (which I find confusing because this brooch appears to be gold-tone, not silver, (?). My brooch does have it’s own mark which appears to be, “STER. PO”- a mark I am not familiar with-, (see pics and see what you think). Can anyone help me ID this piece? As always- many thanks! -K