Usually it is from one gold coin and upwards.” (Shopkeeper)
In Japanese yen that would be around one million yen.
Given that it was an engagement ring presented between nobles, I would say it was a moderately appropriate amount of money.
Certainly the market price in regards to marriage rings would yet again be a different one.
“Such an amount is normal, huh?” (Wendelin)
“That is correct, I doubt that it is a good idea for noble-sama to get something of too poor quality in these circumstances.” (Shopkeeper)