English translation: Sales pitch, sales angle; hook
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Explanation: I remembering asking this question myself, but glossary isn't being very forthcoming!
The shades/tones/colours are the key to selling the product (rather than how long they last, how they condition the hair, value for money whatever). They are the ace up the sleeve, the gimmick, the plug!
They are going to plug the colours.
The colours are the main sales pitch / hook (to catch the customers!)
Our colours say it all
Defined by our range of colours/shades
Hooked on our colours
Sold on our shades
Trademark tones
The colours will grab you
etc etc
I chose 'sales pitch' as I recognised the term. 'Angle' looks good too. I imagine if I knew more about these matters that I'd find 'hook' is the used term among advertisers, but I don't know enough about this. All of the various responses were helpful and often entertaining! I'm extremely grateful for all the help and for the suggested translations. 4 KudoZ points were awarded for this answer
The translation workplace 
peer agreement (net): +6
