We check #22656 should be charged 15% off restocking fee, so it is $213.639($251.34-$37.701).
If it is correct, so the total store credit for #19978+#22656 is $329.999.
$515 for this ring with 2ct(7*9mm) astro smoky spark grey oval moissanite center, GHI color 2.5*4mm pear, 1.8mm round, 1.5mm round moissanite in 10k uplated white gold. Size 5( euro shank,- Cathedral setting with a bridge that is 1.4mm thick)
With 20% off, you should pay $82.001($515*0.8-$329.999)