An 'OG' or 'Original' item is an item originally from Closed Beta or Limited Early Access that the player obtained during that period and not via it's later quest re-release.
'OG' items were created by the collectors market in response to most Closed Beta items being re-released, making them worthless.
Those items being worthless makes it impossible for F2P players to obtain Season Pass items, which are paid for.
'OG' items are not important to the vast majority of the playerbase, and may outright be disregarded by general trading.
However, collectors and those involved in higher-end trading will usually value OGs at a far higher value to their RR counterpart.
Sort of! In an announcement made in roughly December 2020, Wildworks confirmed they would be adding in-game tags to items obtained before May 20th 2020.
It's unclear whether these tags will only be added to Chest & Quest items, or all items (including craftables and minigame rewards)
This update has not yet come out and is on the back burner.
You WILL be scammed or WILL scam others if you trade without understanding them.
It is best to wait for Closed Beta Tags to be released.
There are two main methods, both start with:
1) Open your inventory
2) Go to the appropriate category (accessories or furniture)
3) Next to the search bar, click ABC and change to Newest
Now, scroll to the bottom and look for one of two things:
If you own SP1 items:
If your item appears below any SP1 items, then they are OG.
If you were a Closed Beta Tester:
Compare your items to currently un-rereleased CBs. Those are:
Blacksmith Mask, Ichimegasa, Flaming Lotus, Tricorn Hat, Shoulder Snatch, Shimmer Sword,
Draped Hood, Toad Hunter Shawl, Toad Hunter Hood, Toad Hunter Bow, Toad Hunter Leg Wraps,
Toad Hunter Tail Wrap, Sorceress Hat, Leather Bracers, Shard Ring, Patchwork Pouch,
Longbow, Diamondlion Slippers
Courtesy to multiple TD members for this list.
If you have any of these items, look them up on the Feral Wiki or ask in a Feral chat and compare them to the item you want to date.
This method is not foolproof, as you may have missed out on multiple quests or months of items that make it difficult to date your items.
Short answer is: Not for definite.
Long answer: The best ways to prove are to take full-screen recordings of you scrolling through your inventory and send them to your trade partner.
You may also need to take a video of you adding the item to your trade window, as the trade inventory can mess up ordering of items.
SCREENSHOTS ARE NOT ENOUGH.
Inventory screenshots can be doctored extremely easily.
DO NOT trade for OGs if you are not in contact with the person via an external app and can recieve video or screenshare proof from them.
IT IS NOT WORTH IT.
If ANYTHING about your trade partner, trade, the proof they send or any other number of factors seems off, then decline!