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#### Card Weight

#### Guest Article

Written by: Neil Troy

Summary:

Cards in LP/NM condition from Unlimited Edition should be between 1.65 - 1.82 grams in weight.

When it comes to authenticating Magic cards a common technique is to weigh the card in question. The concept is reasonable: the card stock, the ink, and the number of layers are controlled in a manufacturing process so the cards should be close to the same weight within reason.

The goal of this article is to establish a guideline with regards to Unlimited Edition, establishing what the acceptable range of weights are.

Previously people have made calculations based on the weight of multiple Unlimited cards, and divided that weight by the number of cards weighed, thus determining an average weight for the cards in question. This analysis however will look at the distribution of individual card weights in order to better understand which weights would constitute an abnormal outlier.

To do this 1,550 unlimited cards of all rarities and colors were measured individually. All cards were NM/LP to negate the impact of wear or added dirt on the total weight.

Note: this is a measure of Unlimited cards in 50-60% humidity, significantly different climates may may produce slightly different results.

The scale used was determined to be accurate with .005 grams. All measurements were allowed to stabilize for 2-5 s, and if a measurement appeared to be off, the process was repeated until a consistent reading was given. Calibration of the scale happened several times through the measuring process.

Figure 1 shows the distribution of weights. The distribution has signs of being a normal distribution and for the sake of simplicity we will treat it as so. The mean NM/LP Unlimited card weighs in at 1.735 grams with a standard deviation of .016 grams.

The lightest card weighed was 1.67 g. (an Ironroot Treefolk), and the heaviest card was 1.80 g. (Blue Mountain).

To back check averages three random piles of 50 cards were weighed and the average weight of a card in these piles were: 1.734 g., 1.738 g., and 1.736 g.

##### Figure 1. Weights of NM/LP Unlimited cards

Sample size: 1550 cards

For those less experienced with distributions what we are graphically seeing is the weight of every single card measured. Each card gets counted in a column and the ensemble is presented.

Considering this a normal distribution we can start making some claims about a random card’s weight and how that relates to its authenticity. For a normal distribution we can infer the likelihood that a single measurement is part of the population. A common way people talk about normal distributions is that an N* standard deviation away from the mean value encloses XX% of the population, where N is an integer and typically is taught as:

1-sigma = 68.3%,

2-sigma = 95.5%,

3-sigma = 99.7%

In application let’s assume we come across a random Unlimited card weighing 1.77 g. This card lies just outside of the 2-sigma interval. Meaning that this particular card deviates from the mean more than ~96% of the cards weighed. Based on this it seems reasonable that the card has an authentic weight. However a stack of 50 Unlimited cards with a mean of 1.77 g would be a suspicious weight.

An LP/NM Unlimited card in a similar environment would be suspicious if it weighed less than 1.65 grams, or more than 1.82 grams. These cards would be just outside a 5-sigma event which puts them around a 1 in 2 million event.

When we approach less than 1.60 grams and more than 1.85 grams, it might be possible that some legitimate Unlimited cards exist at those weights, but they would have to be outliers related to printing errors, which would be visible on the card.

Note: These claims are based upon environmental factors and the condition of the card, paper loss and visible dirt can influence card weight in either direction.