Girlfriend has thin black lines on some of her finger nails. these appeared about 2 weeks ago. should we be worried?

Dermatologist: consultation is required as is direct observation to make an accurate diagnosis.

Get checked: Black stripes down 1 nail may be subungual hematoma. Red or brown streaks may be splinter hemorrhages. Brown/black lines from nail plate to tip are often seen in people with dark skin & are normal. Subungual Melanoma can cause nail ridges & dark colors of cuticle. It most often effects the thumbs or big toes. Dark lines may be due to other illnesses. Get checked out when in doubt.