Necktie pin with a black opal-like stone

This is a tie clip with a black opal-like stone!
It has a rich play of color and is eye-catching ( > > )
It looks like an opal made by pasting pieces together, but it has a nice touch and is wonderful ( > > )

The weight is about 4.5g!
The length is about 4cm ( > > )

This seems to be an old tie clip that was in the house, but it's been in the dresser for a long time, so I'm putting it up for sale!
Please refrain from purchasing if you intend to resell it m(_ _)m

There is some kind of engraving on the back, but the meaning is unknown m(_ _)m
The material of the base metal is also unknown. I don't think it's a material-specific item since it's a tie pin, but please refrain from purchasing if you are particular about the material m(_ _)m

If you are looking for an opal-like tie clip, please consider this one ( > > )

I am also selling other items from my grandmother's house, mainly accessories such as K18, 18K, K10, platinum, silver, and other rings, necklaces, earrings, and piercings ( > > )