I’ve had this Engagement ring close to a week and hadn’t noticed it. Today in the car the light hit it at the perfect angle and it was very clear. Now I can’t un see it when I look at it. If I walk into a jeweler could they tell me?It looks like a feather which is like an internal ”crack”. Check with a Loupe for any surface reaching fissures or cracks by examining each facet with the light hitting it to see if you can see a line across any facet (s). If any inclusions are surface reaching that can affect the gems stability and possibly value as well.