Here is an artist made necklace made up of different types and colors of agate. There are nine large agates that measure approximately 7/8" X 3/4". On either side of them are black aurora borealis crystal beads. The smaller beads measure a tad over 1/4" in diameter. The toggle clasp is stamped 925 for sterling. The necklace measures 22.50" in length. Some of the large agate pieces have cracks but I think that is the nature of the stone.
Vintage Artist Made Agate Necklace