IT'S the elusive action in make-up application where so many of us try and fail on a daily basis - getting your foundation shade spot-on.
Making the wrong choice is fraught with beauty perils - first there's the dreaded tell-tale line on the neck, or obvious 'mask' of ill-matched colour.
The problem isn't confined to the skin, either - certain lipstick colours might make you look like death warmed up and a poorly-chosen blusher could give you anything but a rosy glow.
Thankfully, there are clever cosmetics that practically mind-read your skin tone for you. They work by adapting to the wearer's natural chemistry and adjust accordingly, providing the perfect hue for their colouring.
Sound too good to be true? Read on and revolutionise your make-up routine.
COLOUR ME BEAUTIFUL
Just like fragrance that sits and smells differently on every individual, a lip colour that looks amazing on your friend might be anything but flattering on you.
Colour-adaptive make-up works like a tailor-made suit, being the perfect individual fit.
Rupert Kingston, creative director at New CID cosmetics, explains: "Colour-adjust make-up usually works with PH-sensitive pigments.
"Although all skin is slightly acidic there is a slight PH variation between each individual, which is why there's a different result when worn on different skins."
Test for a positive reaction on your face, cheeks, lips or all three.
ACE YOUR FACE
Everyone's skin tone is different, so having a foundation that adjusts to match your complexion is the hassle-free way to finding your perfect shade and achieving a flawless finish.
If you're choosing a colour-adapt foundation, you still need to look for your closest possible match - it's not a one-shade-fits-all solution.
Lancome's Color Ideal Precise Match Skin-Perfecting Makeup SPF15 (£29), offers six shades while New CID's i-Perfection Colour Adjust Foundation (£26), has eight.
Kingston advises: "You should decide on a shade that is closest to your neck colour, to avoid a nasty tide mark.
"Apply the colour to your jaw line and blend well. Then wait at least 60 second for the foundation to change colour - it should all but disappear."
BESPOKE YOUR BLUSH
Embarrassing moments aside, if there's one place that gives off heat it's your cheeks, which is where colour-adjust blushers really come into their own.
"Most colour-adjust blushers work with the temperature of the skin, changing colour to accentuate your natural flush," says Kingston.
"With this in mind, try the cream textures and apply to the apples of the cheeks, blending with a clean finger."
As they're usually heat-sensitive, as soon as the pigments warm up they change colour.
Smashbox's O-Glow (£16.50), is the innovative pretty pink flush to experiment with. Spot the glow as you watch the pink-hued gel react with your skin chemistry and turn into the shade you blush naturally.
LOVE YOUR LIPS
If you haven't worked out whether you're more of a classic red or fun fuchsia kinda girl, let a colour-adaptive lip make the decision for you.
"For natural sexy, bitten-looking lips, have fun with some of the stains on the market," Kingston suggests.
"They change colour with your mood (apparently) and can look a different colour on different days, depending on the temperature of your skin."
For a more intense look, opt for a lipstick or stain, like DuWop's Private collection (£19 each) - colour-changing lipsticks with a rich pigment that change within five minutes to leave behind the ultimate perfect shade.
Keep things fresh with a dewy gloss like JK by Jemma Kidd Lip ID Colour Adapt Gloss (£10), or L'Oréal Paris Studio Secrets Universal Lip Glow (£8.49) - a made-to-measure balm that adapts uniquely to the heat and moisture of your lips.