Brooch Vtg Bar Style Brooch, Gold Tone w Blue Rhinestone & Faux Pearls

This is a beautiful unsigned vintage bar brooch that features a rectangular-cut, deep blue rhinestone
with four faux pearls, two larger and two smaller, flanking the central blue stone. The setting is in an intricate gold tone scrollwork/filigree details that extends outward to form the bar shape. It's approximately 2 1/2 inches long and approximately 1 1/4 inches wide at its widest point. The only thing I see is that the foil backing has a darkened silver spot (refer to the to the last picture). I am not sure if it's intentional to give the rhinestone a different color?? Aside from that, it is still very beautiful.