The Lovers is a form of Shibuichi that can be called Continental Silver more than Shibuichi, with 80% silver, which gives the total looks of Sterling but lower price. The idea happened when playing with combinations to add a golden tint to silver and different experiments like using silver coins from different parts of the world. Do you know that some countries don't use silver 925 as we do? Some use silver 900 -common in Europe- and other countries use silver 800 due to the highest durability. 
The rings that stack into each other were made Sand Casting the forms with the stone set into the mold for the molten metal to embrace them! High heat made the dark Sapphire and the Rubi get darker, so from a distance the stones look black. Somehow, the light reflection in the pictures -sunlight- show them with a bit more color than I see with my eyes!
Why "The lovers"? Because they were made to "fit like a puzzle", the taller ring's stone tops the shorter ring stone like a protective embrace. They go together -anyway you can wear one at a time, they are designed to provide the bold look trending in some Jewelry scene where bold is beautiful-
One of them is a BIT larger to accommodate to the finger shape since both are thick.
They are size 9 1/2 -tall Sapphire-, 10 -short ruby-