There are 12 TONES in the Colour Basics deck.
Six are Tones of the Corner Colours, and six are Tones of the Connector Colours.
Because they contain equal parts of both the base Hue and Middle Grey (which is equal parts Black and White), they can be grouped as Tones, or with their colour family.
There are 60 TONES in the BTC deck.
Simultaneously faded by White and shaded by Black, a Tone may have as little as one part Hue, but it still maintains its identity within its colour family.
There are no 'half Grey, half Hue' Tones in the BTC deck.