Can you please give me an ideas as to the value of these stamps?

by Charlie
(Middletown, NJ, USA)

From what I have been able to find, these are a pair of 1881 2 1/2 pence stamps, either aquamarine or lilac in color (I'm colorblind) with a profile of Queen Victoria. They're from plate 23, and have some sort of crown watermark. I believe that they're unused (though I do see some dark smudges on them), but have some creasing and wrinkling. One of them has a discolored area along the perforations. The glue appears to be original, and there are no signs of them having been hinged.

Thanks in advance for any information you may provide.