I purchased this about 10 years ago at H.P. FRANCE, but I don't know the brand. (It might be e.m.) Approximately 20mm. It's very lovely, but my tastes have changed and I don't wear it anymore. Please, someone, use it! ^_^ Decluttering my accessories. More items to be listed. H.P.FRANCE tomorrowland Tomorrowland IENA Ron Herman Accessories