It could be 5 individual pieces of poured sugar/isomalt. They may have made a mold/frame and poured them seperately then put the lens together.
i might be crazy and been staring at it for too long...but could it be just one round piece with the lines underneath? I'm not seeing a ledge of any kind where the white is.
Looks like a circle with a pentagon shape in the center. Either there is an edge or maybe just lines on the underside that start with each pentagon side and continue on curving slightly.