A manicurist may have saved a customer's life after noticing a strange mark on her nail.

When a woman walked into Jean Skinner’s beauty salon for a manicure, the nail technician instantly knew something was wrong.

The client had a “straight dark vertical stripe” down one of her nails, and asked the manicurist to cover it “with a colour dark enough” to disguise the mark.

But Jean knew that the stripe was indicative of a larger problem and wasn’t just a “blood blister”, as the woman had previously been told.

“The nail salons ‘diagnosed’ her a few different ways,” Jean shared on Facebook, alongside an image of her customer’s nail.

"Some said it was a lack of calcium. Some said it was hereditary.

"I did not want to frighten her but I told her she needed to see her doctor immediately... This is melanoma!"

Jean, whose post has been shared over 2700 times - revealed the woman had called her and said her doctor had diagnosed her with "a very aggressive melanoma" that had spread to her lymph nodes.

"Her prognosis is not good," Jean wrote.

She's shared the post - with the woman's permission - to ensure others know to see their doctor if they notice any changes to their nails.

"Please pay attention to abnormalities in your nail beds. Odd changes... can very likely be nothing to worry about," she said.

"But sometimes it is an indication of a very serious disease.

"Please keep an eye on the nail beds - toes and fingers - of your elderly loved ones and your loved ones that aren't physically able to notice changes in the nail beds!

"Early diagnosis can make all the difference."

Cancer Council Australia recommends checking your skin regularly for any changes.

"Make sure you check your entire body as skin cancers can sometimes occur on parts of the body not exposed to the sun," their website reads.

"Remember to look at the spaces between the fingers and the beds of your fingernails.

You should see a doctor straight away if you notice any spot or mark that appears different from those around it, or has changes in size, shape or colour.

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