This is a lovely Omani ring from the 1950s or 60s. This type of diamond-shaped ring is known as Heysa and was worn on the third finger. Omani women commonly wore a ring on each finger.  One style for each ring. They also wore rings on their toes.

This ring is made from silver has hand incised patterns including a central flower motif, which I believe is a symbol of the tree of life. The thick band has granulation on each side. The ring is in good vintage condition and tests as good grade silver.  

The face measures 1.5 x 1.5 cm (3/8x3/8"). It weighs 6.4 grams. The ring measures 4 on my mandrel at its middle (US Scale).