Please help me identity these pearls!

[Cotswoldrose]

Hello! I'm looking for some help. I work in a charity shop. We see many fake pearl necklaces - at least half a dozen are donated every week! Most are plastic or glass. Occasionally we get cultured strands donated, often by Ciro or Lotus. But this week I've found a strand that is a bit different! It's a single strand of 73 pearls with a high lustre, with golden overtones. The pearls are mostly a uniform size, with a couple of minor variations. The drill holes mostly look clean. I can see a chip on one with the nacre showing through (I think!). There are some minor scratches visible under a loupe on some pearls. Each pearl is individually knotted. The pearls are 6mm in diameter. The clasp is marked with a tiny letter M and looks like gold but there is no mark (I will get it tested). However I can't really tell if there is any grittiness when I rub the pearls together, so I am puzzled! Are these real pearls? It's the lustre that's really making me look at these again, as it's so good... thanks in advance for any opinions!

 

[Pearl Dreams]

They appear to be imitations. See the pearl that has a bit of excess swirly coating near the drill hole? That is typical of fakes.

 

[BWeaves]

They look like imitations to me. The gloppy stuff around the drill holes is typical of imitation pearls.

Oh, I see PearlDreams even circled the drill hole.

Also, they have no overtones. The color is very flat.