Antique Vienna Secessionist Bespoke Jeweled Brooch, Fiery Opal, Gems, Silver on Brass c. 1890s

I’ve tried to research that 16-dot in square mark on the back to this bespoke brooch, in hopes I could identify the maker/artist. So far no luck. I would fly to Vienna to research, but of course – pandemic. If you recognize it or can tell me more, experts, please do email. Thanks.  That said, It is a stunning little thing. Worked with intense precision, the recess set stone is fiery opal in a flat-surface which dances in light. The 3 emerald-colored cabochons, each set into a crafted bezel, could possibly be emerald (no testing capacity just now) but we’ll say they are glass to not oversell it. The other settings seem to be mother of pearl. If you look at the crafting, you can tell this is a high quality artisan’s work. Lots of photos to show it off. And likely a bargain to be had by the truly savvy jewelry experts since we’ll price it based on our cost. 

Very good to excellent for age and type, dating to late 1890s to as late as around 1915. The shape, patterning and high quality remind me so much of the Secessionist architecture and decorative arts that are found in abundance in Vienna. A hinged pin and c-clamp back. Note the artist’s mark (16 dots within a square) on back. Measurements noted on photos.