Pearls can not only be dyed but also irradiated - this darkens the nucleus of salt water pearls. Generally it is uniformity in colour in a strand that can help give it away. Blue pearls , as I was told by an Akoya seller in HK make up just 10% or less of a harvest so getting uniform colour from such a small selection is difficult.
Your blues are very pretty - I love blue Akoya ! And I love the shape of your GSS !