Vintage mystery set ruby and diamond ring US size 6.5

The 18K white gold ring is acquired from Japan. it features mystery set Pigeon red ruby with the a total carat weight of 1.53. Side stones are good quality diamonds totaling 0.42ct. comes with JSL certificate Finger Size: US 6.5 ‎ Resizing Available: no ‎ Item Weight: 4 grams product origin: Japan **the certificate made a general comment that “usually, thermal enhancement is performed” for ruby. Please note that it is not a specific statement based on test results to this ruby, but rather an assumption.