Definition of 'Liquidity'
1. The degree to which an asset or security can be bought or sold in the market without affecting the asset's price. Liquidity is characterized by a high level of trading activity. Assets that can be easily bought or sold are known as liquid assets.
2. The ability to convert an asset to cash quickly. Also known as "marketability."
http://www.investopedia.com/terms/l/liquidity.aspWho said we were just talking China? There are precisely zero NPGS coins on ebay.com right now. That is not the characteristic of a liquid market.
If the market for NPGS coins was liquid there would be many for sale on ebay as well as China. Why would anyone grade a coin for $2.50 that 99% of the people on ebay who know what a PCGS or NGC slab looks like wouldnt recognize? NPGS is an illiquid market except China. PCGS and NGC are liquid markets worldwide including China.
Its like US Treasury bonds which are a deep, liquid market with many buyers and sellers, many transactions, so lots of price data, tradeable in many cities in the world through a bank or broker.
Then Joe's Lemonade Stand of Nunavut's bonds, none for sale in New York or London, lots of sales in Nunuvut though. But how do you sell in Nunuvut? Not tradeable in many cities. So do you go to your state pension fund and tell them its ok to buy Joe's Lemonade Stand bonds because there is a market in Nunuvut?
The reason no Chinese sellers on ebay.com have NPGS coins for sale, while they have lots of PCGS and NGC, is there is no market or a very limited market. That means its illiquid.