I bought the Charlotte Tilbury Light Wonder Youth-Boosting Perfect Skin Foundation from the UK a few months ago, so I have been using it for a while. I started with shade #4 which is the deepest Fair shade, but should be labeled Light in my opinion. Fair might fit the first 2 shades, but then Light would be more appropriate to the next 2 shades.
Anyway, Fair #4 is the darkest Light closest to Medium. It would fit a N/NC20 for sure. I wear a NC25 and it's a touch light for me, bu the formula is sheer so it works. This shade #4 is not yellow, I don't see pink it's more neutral. Shade #5 is the lightest Medium. It's better for me as an NC25-27. It's more yellow and warmer. It could work for NC30 I feel as it's sheer. I'd have to see shades #3 and 6 to see how far the shades change. But when I post the swatches below you'll see how far apart 4 & 5 are. A 4.5 would be great as I mix these two sometimes to get that perfect light-medium shade for me. But if I had to pick one it would be #5.
The formula itself is a light buildable coverage to potentially medium coverage. It's not matte. It's not a fully dewy luminous foundation either. It's lightweight and not heavy or greasy. It has a few shimmer particles in it but nothing really noticeable. It lasts maybe 8 hours or so on me. It's not a long last, but for me that's fine. It doesn't clog my pores or break me out. Overall, it's been a foundation I reach for a lot. It's a 40 ml tube that has SPF 15. I like to apply with my fingers, a foundation brush or a Beauty Blender. Depends on my mood and time constraints.
Check out my foundation comparison page here for more swatches.
Top to Bottom: #4, #5.
I purchased Charlotte Tillbury 5 medium. I am medium fair skinned blonde blue green eyes. Not sure of my undertones. My veins are definitely green. Look better in gold jewelry and gold clothes than silver accessories. Is 5 medium considered a warm shade?
It's peachy toned so I would say yes