Thanks for reaching out to us. We want to correct that #21409 which is 4ct（16.5*8mm) marquise moissanite.
You paid $239.2 for this 4ct stone, and we let you know below semi mount price:
A) $820 for this ring with a 4ct（16.5*8mm) GHI color marquise moissanite in 10K yellow gold. Size 8.5With 20% off, the balance is $416.8
Bezel setting , not prong setting