I've been doing exactly this for about 11 years now on... let's just say a very large number of cigars. Use a black Sharpie to avoid fading. I've seen zero detrimental effects.
I also Sharpie boxes and the cellophane of bundles for intact boxes/bundles, then later when I remove a cigar from them for immediate smoking, I of course don't Sharpie it (I just saw the date it was from on the box/bundle), but if I remove it for smoking later (where I might forget what bundle/box it came from) or for gifting, I write the box/bundle's date on the cigar's cellophane. Bonus for gifting: the recipient knows the age.
I do a simple MM/YY.
It's a great dating system. Decentralized, no ledger or Excel spreadsheet or any of that nonsense. Directly on the product permanently. Readable by anyone including gift recipients, and also your heirs if you suddenly die. If the collection is broken up (you do big-time gifting or you die and your heirs split it among multiple people), the dates are on every individual cigar or bundle/box. Zero effort needs to be made in resolving some ledger/spreadsheet with all the sub-sections of your collection.
Also, if you do it from day one on everything you get, it's near-zero effort as the effort is widely spread out over time. I highly recommend it.
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Pudding Mittens wrote: