Remember not all colours are "web safe"..but this is only like to affect older browsers..
I haven't thought about web safe in a lo-o-ong lo-o-ong time.
Why not use the HTML colour / color codes in your product descriptions..
Keep in mind, regarding Google, that the range of synonyms it returns, though getting wider, is limited by usage, affected both by the number of queries and by what's in the index.
Several years back, eg, we had a discussion about how a zip code in a query might not bring up the placename, as zip codes (in the US) weren't frequently used in geo searches nor in most geo listings.
Similarly, I think it's extremely unlikely that HTML color codes in text would be helpful, unless there are frequent uses of HTML colour/color codes in visible text on product pages, as well as frequent queries for the codes in the product area.
I'd been thinking of Pantone color codes [
en.wikipedia.org...] as the most exact way of specifying a color... but IMO, for most products, they probably wouldn't get any queries or mean anything to most users. In a niche that targets, say, designers or printers, where precise color specifications are important, Pantone codes might be helpful.
Again though, unless Pantone is commonly used in the niche, it's not likely to mean much either to users or to Google.
It would be interesting to see how Google reacted to schema with Pantone name/number combinations over time. Probably the schema format of the name/number combination would have to be more precisely defined.