Thank you for submitting your item for appraisal. This brooch is composed by an oval shape cameo surrounded by a gold metal frame with colorless stones set. The brooch could be also used as a pendant. The cameo is composed by a glossy black stone with an applied three-dimensional female face in profile. The black material could be an onix. The face is engraved white material which is opalescent, it could be a real opal. The pendant is stamped "45.24" ad "D 0.23" on its back. The number "45.24" probably refers to the weight of the whole brooch, while "D 0.23" is the weight of the colorless stones. These are set in the top part of the frame. They look like diamonds, round shape, brilliant cut. Their approximate color could be H and VS clarity. According the color of the metal and the general aspect of the item, it is probably made in 18kt yellow gold. Analyzing the photographs, it is probable that the object dates back to the Victorian era.
Please let me know if you have any additional questions. I'm happy to give you my support.
Thank you.