Why not a Sapphire?
The lovely Mr. Andri, an architect at the Los Angeles based Architecture firm Johnstone Marklee (who also designed hand made weddings studio) Asked us to custom design his bride to be and engagement ring using other gem stone's rather then a diamond. requesting the use of hand crafted techniques to look very hand made and original.. here is the happy bride with her deep blue sapphire ring set in 18k gold.
It was all she needed to add the something blue on her wedding day..
here are some images of the ring...