White bloom on Lapis Lazuli stone - Help please

[LapisLazuli]

Hi,
I am new here and am looking for a little advice.
I carried out a small solder repair for my sister, on the clasp of a sterling silver necklace with a lapis lazuli pendant. It has sentimental value but I'm unsure of actual quality ( she purchased it on holiday) The stone had previously fallen off and been repaired by her husband, with superglue.
Because of this, and knowing that Lapis can be damaged relatively easily, I was very careful to keep the soldering and pickle away from the pendant.
However whilst I was rinsing the piece (post-pickle) I was called away and mistakenly left the necklace in a ramekin of water overnight. The pendant was draped over the side and not submerged at all.

Now there appears to be a white, speckled bloom or haze or discolouration on the surface of the stone. I am baffled and very disappointed in myself, I am only a hobbyist trying to do a favour for my sister by repairing her favourite necklace. Now I'm worried I've somehow ruined it.

I am fairly sure the surface of the stone was pure blue beforehand. I will try to attach some photos to this post.

Is it possible that water crept up the chain overnight and into the stone, damaging it? Seems unlikely but how else could this have happened?

Is there anything I can do to restore the stone back to blue? I tried a quick polish to no avail, and I'm scared to try anything else without asking the experts.

Many thanks for any advice you can offer!