They look like cultured akoya pearls. The surface characteristics on that center pearl look like one of the naturally occurring blemishes found in pearls.
The also look like someone wore them a lot! No doubt they will look better after a nice bath in warm water and a mild soap. (Although, if you have hard water, make that a mild baby wash sort of cleanser instead of soap, as hard water combines with soap to form scum that would be hard to remove.) Let them soak 10 or 15 minutes to soften the accumulated grime, makeup and whatever else is on them, and then wipe them gently with a soft microfiber cloth. Don't forget to clean near the drill holes as dirt accumulates there. Then rinse them and wrap them in a soft towel to dry. When the towel is dry, the silk will be, too. Silk is weakened when wet and the part inside the pearl takes longer to dry, so don't hang them up or wear them until they are dry.
Then take some more photos, including closeups (especially closeups of any blemishes or loss of nacre), against a white background, with no flash. Some closeups of the clasp would be nice as well. Look at the clasp to see any marks indicating type of metal (14K, 585, 750 for gold, 925 for sterling etc.)
Can you also measure the size of the pearls in millimeters? Ot at least count them and measure the strand from end to end. Are they all the same size?
Do you know any history of the strand?