should i buy an antique engagement ring over a new ring?

I am worried it won't be valuable -

here are the stats of rings i looked at in
Platinum -
Center diamond is an old mine cut; 1.0 ct., G,VS2
This ring is $5500 and we can offer it to you for $5200.
C.1915
Platinum. Center diamond is an Old European cut., GIA certified, I color, SI2 clarity. This ring is $8900 and the best I can offer you this ring for is $8100.
C.1915
Platinum, center diamond is an old european cut that is H color and SI2 clarity. This ring is $7500 and we can offer it to you for $7000.
C.1920

are these fair prices?