Now that's a gorgeous ring, too!
The Strack book doesn't show any bar pearls but lots of other baroque shapes. If this ring was made in the 70's it could be Biwa, but without knowing the provenance it is very hard to say. The "stick" pearls sold today are often called biwa, and unfortunately that is not correct. These could be AAA stick pearls. They are still all nacre and very lovely. I am not sure if there is a test for Biwa pearls.
Pattye