Understanding the Argot of Antiquities Dealers and Auctioneers.

This tongue-in-cheek dictionary is quite good, a series of tweets from Incunabula@incunabula ("Bibliophile. Rare book collector. The history of writing, and of the book"):

 A brief 10-point beginner's guide to understanding the language of antiquities dealers and auctioneers.
1. Offered with Certificate of Authenticity = Faked. We were unable to get any independent scholar to authenticate this item, so we've printed our own certificate.
2. Legal to buy under US Statute covering cultural patrimony Code 2600 Chap 14 = Without provenance. If we had any we would have said so. We don't.
3. From a European collection = From Turkey.
4. From an old European collection = Reserve stock of a Turkish antiquities dealer.
5. From a prestigious old European collection = Reserve stock of a large Turkish antiquities dealer.
6. From a Turkish collection = From Syria.
7. From a distinguished private collection = From the reserve stock of the Baidun or Barakat families.
8. Some restoration = Glued together from tiny pieces.
9. From an old collection mainly formed in the 1960's = ...but also partly in the 1970's, 80's and 90's.
10. By family lore acquired by the owner's grandfather in the 1950's = No documented provenance.

A few more:
11. Hence by descent in the family = everyone who could personally vouch for the provenance is dead.
12. Acquired around the late 1960's = Acquired after 1970.
13. Will reward further scholarly study = No reputable scholar has shown any sign of interest in this piece so far.
14. Sold with an Art Loss Registry Certificate = No provenance, but we offer an official-looking certificate confirming it's not on any register of Nazi plunder.
[Specifically of papyri and cuneiform tablets]
15. Not yet transcribed or translated = standard administrative text or letter which we've privately verified before offering for sale is definitely of no wider interest at all.
16. A very similar piece sold at Christies on... for $... = the similar piece at Christies was bigger, older, more beautiful and, unlike ours, had provenance.
17. A piece of immense importance for biblical scholarship = even Hobby Lobby wouldn't touch this turkey.
18. From an important East Coast collection / From a West Coast collection / From the collection of an Edinburgh surgeon / From the collection of a former Princeton professor... = There's no provenance at all, but we hope nonetheless you'll find this anecdotal info distracting.
19. Anecdotal evidence indicates = My pappy told me this story once around the campfire.
20. Rare = Not rare.

UPDATE:
The author notes:

This tongue-in-cheek list is based on experience with, specifically, the antiquities trade. It's not generally applicable to other related areas like the rare book business. It's above all a call to read between the lines - to notice what is NOT said, as much as what is said. I'd be happy - within the constraints of Twitter - to elaborate and explain any of the 20 points below on request. Each is based on - usually multiple - real world examples. When you impose legal constraints on a commercial sector - which is what the requirement for legally valid provenance has done to the antiquities trade - such businesses will inevitably attempt to circumvent these regulations, while still staying within the letter of the law. So when studying this sector, or, if you're an ethical collector, trying to make buying decisions, you need to parse the language used in the descriptions of antiquities carefully - none of it is accidental, and some of it is intended if not to mislead, at least to misdirect.

Andy Brockman @pipelinenews, equally tongue-in-cheek calls it: "An essential guide to auctioneer and antiquities dealer Newspeak". I think it just goes to show what suckers the majority of people buying antiquities without proper paperwork actually are.