Color Variations On Red Revenues?

Similar to blue having the occasional ultramarine variant, or orange showing the occasional vermillion, are there any color subtypes for the red issues?

I have this 25c Certificate that appears to be a deep brick/lake red. The paper is very white and impression clean much like a 1st issue silk paper, but there are no fibers.
I'll put it next to other commonly seen "red" shades:

All first issue revenues have shade varieties. Some were deliberate; to prevent cleaning and reuse, all the dark stamp shades were made lighter, and all the light stamp shades were made darker over the life of the issue. Also these were produced by daylight or oil lamps with no electric lights. Every day the leftover ink would be mixed with a new batch, and as long as it was about the same by their standards, it was fine.

BTW, the stamp to check for silk is the one in the middle with the 1870 cancel.

Thanks for putting it into perspective, Bart. I checked for the silk on the 1970 but it seems to be a regular, old paper issuance:





Dan's website https://revenue-collector.com/ explains that 1st issue silk papers can exist without showing the actual fibers, implying (and is certainly true) that there are other characteristics that silk papers possess. The paper of the "Certificate" above seems like such a thing, as it doesn't feel like typical old paper.

While certainly true, the only way to be sure (or to get a cert), is to have silk fibers visible in the stamp. Otherwise it opens up a whole can of worms better left closed.