Hello Halim, Yes, there are occasional albinistic specimens of Nautilus pompilius. They are extremely rare. I believe such a specimen was offered at the Conchologists of American convention a couple of years ago, either as a raffle prize or an auction item??? Here is my take on the shell grading system. These descriptions are not "official", but they work for me, and I feel that they accurately reflect the intended purpose of the system. I am open to other opinions: "gem" - a specimen with no flaws detectable by the unaided eye "fine plus plus" (f++) - a minute flaw, difficult to detect, even on close inspection "fine plus" (f+) - one or two small flaws, not readily noticeable except on close inspection "fine" (f) - one or two significant flaws, noticeable on casual inspection, which do not greatly compromise the scientific or aesthetic value of the specimen "good" - major flaws, but still showing the principle identifying characteristics of the species "Gem" is usually described simply as "flawless", but I prefer to describe it as above (pardon my compulsion for accuracy - I'm a scientist). In my humble opinion, an absolutely perfect shell is an extreme rarity. Give me your best "gem" cowrie and a good 50-power microscope, and I'll find a few flaws for you. But such microscopic imperfections do not require that a shell be downgraded from "gem". Some dealers list shells as "fine+++" or "fine++++" or "fine ++++++++++++++++", to indicate a specimen that is virtually - but not QUITE - gem. I suppose this is warranted in some cases, though generally speaking, I think the use of extra "+" signs just confuses the issue. Others use "gem-" (gem minus) for the same purpose, or simply describe the specimen as "near gem". To my way of thinking, "fine++" is supposed to mean "near gem", so I usually just stick to the basic categories listed above. I base grading on both the severity and the number of visible flaws. A shell with one minute flaw would be fine++. A shell with a more significant flaw would be downgraded to fine+. But a shell with several minute flaws, as severe as the flaw on the fine++ specimen, would also be downgraded to fine+. Paul M.