Not sure how much you know about the genetics in chinchillas, so sorry if it's too basic
TOV is said to be a colour, but imo it's actually a pattern. It gives a dark back, lighter sides and white belly (if no ebony). It also gives a dark mask.
With some colours TOV can be very hard to see. This goes for colours with wite in them, and ebony in them.
Tan is a fancy word for a chinchilla with beige and ebony in it.
Because ebony, like TOV, is more of a pattern than a colour (even though it can make the colour darker), it can be very hard to see TOV in ebony animals.
One of the sure signs of TOV is that "Dark-light-white" pattern, but the ebony cancels that out a bit.
This is his sister from a former litter.
She is a TOV Pink White Ebony.
It's near impossible to see the TOV and the Ebony in her. If she was all white, I would have to call her poss. tov and ebony.
The mom (white girl on the pics with the boy Dino) is a TOV Pink White. I only know this, because af her daughter that has some spots on her body, that shows me she's tov pink white ebony.
So it can be very hard to see TOV in animals. And ebony if the animal is white, but imo TOV is a bigger challenge
Did that make any sence at all?
Sorry if the spelling is bad. I do not have the program installed that checks my spelling on this computer.