Without a lab report you can’t tell from a photo if a gem is as stated and/or if it is treated.
As with all gemstones there is a range of hue and tone that can attract a premium price. Yes, Imperial Topaz, untreated and with a fine pink hue is more desirable and therefore valuable.
The ring is the photo is pretty, but just because the seller calls it “Imperial Topaz” is neither here nor there if the tone and hue is not sought after and therefore a premium price point. Of course the value of the gold and diamonds is a large part of the rings price/ value.
AJS gems has a nice selection of Imperial Topaz and the prices range from $20 a carat to $2,000 a carat or so.