Start with a picture. A photo is fine... and a magazine pic is good too. Get a flat backed glass stone, a coat the back of it with E-6000 or superglue fix-all adhesive. After it cures for a few minutes, press it onto the pic. Twist or press (or both) So there's no bubbles then let the glue dry for at least an hour, but longer is better. Overnight is best.
Using thin scissors. Or a razor knife, trim around the edges.
To crochet the setting, wrap a loop of thread around your finger, pull a loop through and ch 3. 11 dc in loop, pull loop tight. Sl st in top of ch 3 to close ring.
Rnd 2: ch 3, 1dc in same st, 2 dc in every st around, end with a sl st in top of begining ch 3.
Rnd 3: ch 2, working in back loops entire row, hdc in every st around, working.2 or 3 decreases evenly spaced. Close and tie off.
Place more glue on bottom of stone. Pushing ends of thread top inside center, force glued stone into cup, stretching sides over edges.
Work cha and decorative stitch of choice in the free loops of the final round.