It's some kind of fancy pants opal gently rotating back and forth against an all black background. Splendid!
The 34th anniversary is the opal anniversary. I've been looking all over the web for historical information about why certain anniversaries involve certain gift themes but to no avail. My girlfriend jokes that since the 90th anniversary is themed after granite most people should get headstones as gifts. The 100th anniversary theme is probably the pine box.