18mm x 13mm B-Grade low dome oval glass cabochon, also called glass domes, and bubbles.

Size: 17.8mm x 12.8mm x 3.9mm high
Material: Glass (magnifying glass)
Flat Back. These cabs fit the bezel settings listed below.

About the Grading system for the Glass cabochons:

• A-Grade - clear with no visible scratches or marks.
• B-Grade - may have small marks on the bottom or small cracks on the edges, these generally don't show when inserted into a bezel setting.
• C-Grade - small scratches on top, insignificant but there.
• Seconds - with scratches on top, ideal for practising with, or kids classes, or for 'vintage, grunge or rustic', when imperfections are part of the design!
• M - 'mystic', the glass is not crystal clear.
• R - rounded bottoms, these domes are not suitable for using in bezel settings with low side edges, but are ideal in high-sided bezels, or crown edge and filigree edge settings.