Costume Agate(?) Brooch

My daughter calls this brooch the “Ocean Brooch” because it looks almost like the waves of the ocean. As I post this brooch, she is on a plane from Miami to Martinique, and for the next seven months she will surely enjoy the beautiful waves surrounding the island. I am so jealous!
I am also a bit sad because I miss her a lot. She is the only one of my children who shares my passion for colleting jewelry so far.

Anyway, I have found only one brooch that was similar to my one. It was listed as “Blue Lace Agate” but I am not sure if this is correct. I think it could also be some kind of dyed quartz.

Any ideas would be greatly appreciated.

Thanks for looking:)