Here's a quick guide of things to look for that could be the sign of something more serious...
Instead of the normal pink colour, your nails may appear pale. According to WebMD, this can be linked to more serious conditions like anemia, congestive heart failure, liver disease and malnutrition.
This can be a common side effect of smoking, which stains your nails a yellowish hue. The other common cause is nail fungus or psoriasis. However if you frequently use nail lacquers or acrylic nails, this can also be a cause.
According to Healthline, blue tinged nails can be a sign that you're experiencing a lack of oxygen. This could be caused by diseases like asthma, emphysema and pneumonia.
Black/Brown Line Down Your Nail
This is particularly important to look out for as it could be a melanoma. If it grows or changes, go see your doctor about it. Melanomas have been known to occur after gel manicure procedures from exposure to UV light.
If your nails curve up at the edges, it could be a sign of anemia, heart disease, hypothyroidism or hemochromatosis.
White Spots On Nails
This is generally the sign of trauma to the nail, for instance being jammed or banged too hard. It's usually not a sign for concern.
Puffiness Around The Nail
If your skin around your nail is all red and puffed up, it could be the result of lupus or a connective tissue disorder. It could also be the sign of an infection around the nail fold.
If you are concerned about any problems, go see your GP.