It is very hard to evaluate pearls photographed against a dark background, in not very good focus and with lack of closeups. Please take more photos and we'll give it a go. White background (paper towel is good) no flash, sharp focus and lots of close ups of any flaws. Check especially near the drill holes.
Do the clasps have a metal mark? A photo may help us there as well.
Here are 2 quickie tests that are usually helpful in deteriming real vs. fake:
1. Real pearls are cooler than pearls made from glass or plastic beads. If you place these 2 necklaces in the same temperature environment as any other pearls you have that you know to be real (or that you know to be fake), and leave them there for about half an hour, then you can compare their temperatures. Hold the pearls against your lips, which is very sensitive to temperature.
2. Rub 2 pearls of each necklace together gently. Real pearls have a gritty feel to them because of the structure of nacre. Fake pearls tend to glide smoothly against each other.