MNH, MVLH, MM, UM, gum, watermark

What is MNH, MVLH, MM, UM, gum, watermark?

I bumped into a tiny Ching-dynasty dragon-picture stamp from my grandparents' stamp collection about one year ago. With parents not much helpful in terms of its true identity and friends only familiar with facebook's widgets and Nintendo's Wii, I googled for China stamp information, read plenty, bid on eBay. It is time to write up what I have gathered, and to dedicate the articles to my parents and grandparents. This is the most expensive hobby I have ever had, in terms of how much I pay, and in return what I get, most of the times, is a small piece of paper, which is known as a stamp, an old stamp.

... start with some jargons
M = Mint. Can be used or unused. "Mint" simply means no postmark on the front.
MM = Mounted Mint. In the old days, stamps could be mounted inside stamp album through many ways. Simply put, "MM" is the opposite of "UM".

UM = Unmounted Mint. Or almost equivalent as "Mint Never Hinged". There may be subtle difference between "UM" and "MNH".

MNH = Mint Never Hinged. Stamps could be mount in a stamp album using small paper hinges. A hinged stamp usually has small trace in the gum, even after stamp removal from the album. "Mint Never Hinged" means the stamp was not even hinged. For stamp older than hundreds year old or before World World I, most are hinged.

MVLH = Mint Very Light Hinged. For popular and expensive stamps, the degree of hinged can command a significant price difference. Therefore, stamp sellers would like to add "V" to indicate that the stamp is almost MNH. For expensive stamps, stamp certificates to verify stamp authenticity and detail stamp quality are important.

gum = The layer of glue at the back of a stamp. An unused stamp should have full gum at the back.

NG = No gum. The stamp was used before.

RG = Re-gummed by expert. The stamp was likely used before. The stamp is considered as high-value usually. To regain the MNH look, a new layer of gum is added back. However, a RG stamp should be much cheaper than MNH. It is a like a piece of old furniture fixed up with modern paint.

centered = a stamp well-centered is desired. However, rarity rules. A stamp off-centered in a rare style may worth more. Pricing is quite subjective, up to the buyer's preference and collection concentration.

watermarked = picture at the back of a stamp.  An example is the Crown picture at the back of old British stamp at the gum layer.

F = Fine. Also VF < XF < PF. If a seller says "XF", I would not accept it anything above "VF".

"greased", "thinning", "perf tip cut", "oxidized" are some conditions of a stamp. All of these lowers the value of a stamp.

The above should be sufficent for one to intrepret most stamp descriptions.