'My new look - what do you think?' the fashion stylist asked her 70,200 followers.
Some fans were impressed by the almost-grey dye, calling it 'stunning' and exclaiming 'Love that colour! Very French chic!' However, others were less enamoured, with one commenting 'Noooo! You look much older!!!' - and some even suggested that it may be a wig.
We have to say, we've fans of the ash blonde on Trinny, especially with her tousled, voluminous bob cut.
What do you think of Trinny's makeover? Let us know your thoughts in the comment box below.
- Tested: Best and worst sun creams
- What celebrities really eat in a day - revealed!
- Celebrity tattoos
- How to get a cool night's sleep on a hot summer night
- The X Factor contestants: Where are they now?
- Celeb bikini gallery
- 15 bloated stomach causes
- 10 tips for getting rid of cellulite
- Healthy juice recipes: 12 detox juices you can make at home