Thanks for your interest in our laser cutting.
We aren't equipped to measure the engraving depth on glass, but we can generally adjust engraving depths quite a bit by varying the laser power. However, the scale of the parts you are looking to cut (by way of engraving, if I understand correctly) is way too small for us; we cannot reliably handle such tiny parts. Perhaps you can try contacting jewelers; some of them might have lasers more suited to your scale of parts.
Just to give you a rough idea, the smallest part we can practically cut and handle might be a 3-mm-diameter circle out of 1.5-mm material (if you aren't picky about the yield or how circular the circles are). The parts we typically cut range in size from 1" square to 24" square, out of materials that are 1/32" thick up to 1/2" thick.
In case you ever have a need for larger-scale parts, please do read our laser cutting guide. Some sections of note are Materials for Laser Cutting and Capabilities and Limitations of Custom Laser Cutting.
I'm sorry we can't help this time; best of luck!