The most common way of sizing your collection is through an actual count of all dice, seems simple. That is what I thought until Kevin Cook came into my life. Kevin holds the Worlds Record for number of dice in a collection. At the time of this writing it numbers 29,577. That figure changes almost daily but right now his official counter, which appears on his web page, says 29,577. Kevin owns more dice than 29,577 but he probably cannot tell you what the absolute number is because he doesn't count that way. He has very specific rules which determine the number of dice in his collection. You will have to dig through his site to find his rules. My rules are the subject of this writing.
Duplicates are one of the largest issues. What constitutes a duplicate? I have 100s of average sized white dice with black pips. I have so many I could make small sculptures with them. Perhaps I will someday. It is either that or get my slingshot out and do a study on the aerodynamics of the 6 sided dice. That would be fun too. But the true question is, do they count towards the official total of my collection...no. Actually at one point in my collecting history I did count them but the time of having to impress with numbers has gone from my life. Now my collection is more about what speaks to me and what I know will impress those I feel important to impress. A far smaller population then once was needed. All the same i do like to quantify my collection if for no other reason than conversation.
Here are some of my rules...
Pipped 6ds are counted in pairs.
Unless I own only one
Unless it was intended to be a single
Unless for some compelling reason they would be counted as more than 2
Polyhedrals are counted as singles
Unless a set is more than one
Casino dice are counted in pairs
Unless I own only one
Game dice are counted as the number required in the rules to be part of the game
Unless that number is unknowable like Xenon or Lego dice
Collectible dice are counted as singles even though the rules of the game may allow for multiple copies of the same die.
"Vintage" or antique dice may be counted individually because hand work or wear has made them unique
My official collection count right this instant is 826. Strange, somewhere in a previous post I mentioned something like approaching 4000 dice, 826 is a far cry from 4000. Rest assured this unusually low number is only low because I am currently entering all my dice into a spreadsheet. The official tally with the above rules applied constantly updates at the top of the worksheet. I have 3 large plastic bins yet to document. After everything has been entered I will have approximately 4000 dice. As I enter these dice i am defining my rules on the count. There will be issues yet to decide...I am sure. I will update the above rules as new ones are created or old ones get modified.
In later writings I will be discussing the very definition of a die. This can also effect the total number of dice in ones collection.