buuutttttt... treated gemstones really do loose their value at the moment they are treated (even if it's "common"), which they already do when put into a ring or something else - so I personally wouldn't rely on value, if not bought as a solo stone.
And even then, you'll never know what the market wants, what buyers ask for (see my last sentences) and so on... So: ig it makes your heart sing, and those rings do look great, buy it. Regarding prices / Resale value:
When in doubt, I tend to look up the following page
buy competitive-priced gemstones (faceted diamonds and colored stones) in various cuts and colors online
www.carat-online.at
it is available in English, so you can compare prices
. By clicking onto the picture of the stone you'll see if the stone was treated, it'll be indicated including the treatment itself.
Mind, that these prices are quite reasonable, so you could add something to the prices they ask for.
Additional information: my jeweler (who got robbed, can you believe it) told me, that actually colored stones aren't that as requested as diamonds, better said: nearly nobody asks for colored stones any more. Lucky me, I got a great Peridot in desirable size for a spectacular price.
So, I'd keep that in mind, that colored stones might become cheaper in the nearer future due to request.