She hits the nail on the head.

A manicurist in Scotland is being praised for noticing a thin brown line under a client’s nail—which led to a melanoma diagnosis.

Stacey Boss, 32, said she shrugged off the mark on her right thumb nail for a while until her nail tech discovered it in November 2019 and refused her a manicure, urging her to go to the doctor instead.

“I was very confused,” said the record company owner admitted to Kennedy News. “I didn’t know anything about how melanoma skin cancer can be in a bed of nails. It was staggering.”

She initially believed it was a bruise under her fake nails.

“I just got used to it, and it wasn’t until someone pointed it out that it was a big, shocking moment,” she explained.

The mother of one visited her primary care doctor before being referred to a dermatologist, who diagnosed her with subungual melanoma, a rare type of skin cancer found under the nail.

The condition can be treated when found early, according to The American Academy of Dermatology Associationbut a melanoma can be fatal if diagnosed too late.

Melanoma of the nail often presents as a dark streak in the nail bed, a split nail, a raised nail or a bump under the nail, according to the dermatology association — symptoms Boss said she experienced.

“It was like a streak. It was like someone had marked my nail with a permanent marker from the cuticle to the top,” Boss described.

She said it kept growing on her thumbnail.

“It was thin and thin and almost as if someone had dented a mark on it. By the end, it looked like a smiley face because of the shadow of the line, the dip and the way the cuticle grows,” she added.

In March, Baas had her nail and part of the bone removed and underwent a biopsy of the nail bed.

There were some delays in her final diagnosis due to the coronavirus pandemic, she explained.

She faces more tests to make sure the melanoma has not spread to other parts of her body, such as the lymph nodes.

She described the removal as a “relief” and admitted that she felt something was wrong with her even before she was diagnosed.

“I had anxiety, my whole body was changing, the line was never gone, it was always there,” Baas recalled.

However, there is a silver lining to all of this – the music fan claims she gets a discount on her scalloped French manicures because she has one less fingernail.

She also hopes to raise awareness about this type of melanoma, and encourage others to take notice of subtle body changes – especially to their nails.

“The nail technician may have saved my life, she was well trained and very aware, more than I was,” said Boss.

Boss is not the only person to receive this diagnosis – in 2019, a beauty queen in Chicago revealed a similar discovery.

Karolina Jasko said she noticed a thin black line, also on her thumbnail.

She went to the doctor for an unrelated infection, and a biopsy was ordered.

Her entire nail bed was removed. A skin graft taken from her groin was used to cover the finger.