The average diamond carat weight for an engagement ring in the United States is about one carat. In the United Kingdom, it's 0.6 carats, and when looking at Europe as a whole, it's even smaller ...

A ring with a 7.31-carat emerald shaped diamond has an estimate of $120,000 - $180,000 . ... It is flanked by two princess cut diamonds weighing approximately 0.75 carat.

As we know, your engagement ring has 1 carat diamond with the colour F and a VVS1 clarity which if natural would be a stunning gem but as this is lab-grown, it wont hold much of a resale value.

Among them are a 8.2-carat blue sapphire ring, set to go for anywhere from $300,000-$500,000, and a 10.95-carat round brilliant-cut diamond set in gold, which will go for somewhere between $40,000 ...