I think this is actually Phos. Cairngorm isn't appeared until that incident, so the one with Cair will always be Phos while the one with Ghost is Lapis, unless the artist say otherwise.

Update:
Found the turmbl version" with #"I love Phos with every character.....all of them" and this belong to a set post of Phos with their important one/partner so it's obviously is Phos so I changed the tag.