Nice button.
And I agree with Vayank it's most likely late 1800 and could have very well been what is reffered to as a " Perfume Button" Minus the fabric on the back.
PERFUME BUTTONS
Perfume Buttons, in my opinion, have the coolest story. Made in the mid-1800's, they have an underlay of velvet fabric with a pierced, ornate brass/copper overlay. The perfumes of the Victorian Era were oil based, and when used on the skin, would soil the women's' clothing. These buttons were designed so women could dab their perfume on the velvet of the button, thus, protecting their clothing and carrying the scent for a long time. Keep reading…you will love this. During the Civil War, women would give such a button, scented with their perfume, to a husband or lover going off to war. He would stitch it under his uniform collar as a reminder of the love he left behind.