You may or may not know it, but I have a serious thing for stones and a lot of experience with what's valuable and what's not (both buying and selling (natural stones), US stones, UK type stones and I've probably sold well over 100 japanese stones). Based on what you mentioned, both of those color adjustments sound to me like they were done to make the stone look more valuable than it is (not saying anything about their performance).
A bone/yellow colored washita that has a waxy look is very desirable, as is a vivid green charnley (I realize you guys can get good charns on the ground in the UK pretty cheaply, but we can't get them here. You can chance across $4 washita stones over here, too, but once they hit ebay, they're not $4).