Most diamonds listed online are not owned by or in possession of the retailers. Instead, retailers have agreements with the suppliers to list them, so you will often find the same diamond listed with multiple retailers.
Is it from Adiamor?
If so, it appears it's just a name / branding for their 'top spec' MRB diamonds.
Many diamond retailers label what they consider top quality cut diamonds. Adiamor uses the term Affinity, James Allen uses True Hearts, Blue Nile uses Astor Ideal, etc. There is no specific information as to what qualifies these diamonds as such and there is no consistency between the retailers. So just because Adiamor labels a diamond as Affinity doesn't mean the same diamond listed with James Allen will be labeled True Hearts. Most diamonds listed online are not owned by or in possession of the retailers. Instead, retailers have agreements with the suppliers to list them, so you will often find the same diamond listed with multiple retailers. Just because a diamond is labeled as such doesn't mean it meets "PS Quality", which is the term used here to describe top quality cut diamonds that aren't branded Super Ideals (which are sold by Super Ideal vendors like Whiteflash, Brian Gavin, etc.).