I'm guessing on the identification of this cabochon as Blue Agate. The sample wasn't much larger than the cab. The color varies from dark blue to light blue, and there is a remnant of a sealed drusy pit, mostly on the back; you can see a hint of the start of the pit on the right edge.

11.5mm x 9.5mm x 5mm.   Weight: 4.10 carats.

Every one of my cabochons is custom cut to take the best advantage of the particular slab from which it is fashioned. Colors may vary somewhat from what is pictured due to differences in computer monitors.

Click the image on the right to see the cabochon super-sized...

BLA003