Belly dancers never use to wears jewels in their navel. In 1920 in the
silent era of film making in Hollywood it was illegal to show bare navel
on the screen. But for entertainment a Harem scene with belly dancing
was much popular in 1920.
Hollywood producer found a novel trick to cover the navel with a Jewel.
During many famous actresses came out to do the dance with few native tricks of sword and knife who could even sing on stage. This image became so popular that real belly dancers now often wear Jewels to look themselves more “authentic”.