The new plate block collector should buy a copy of the “Scott Specialized Catalogue of United States Stamps and Covers” to become familiar with the correct collectible configuration of plate number blocks.The exact number of stamps and configuration of the plate number and other various marking are crucial to the value. Remember that early flat plate issues are only considered plate blocks if they are in blocks of six or larger with the plate number in the center. The exception to the rule are some bicolor stamps that are only considered plate blocks if they are in blocks of eight with two plate numbers. Rotary press issues are considered plate blocks in blocks of four or more with the plate number. Also remember that a never hinged plate block means that there is not a hinge mark anywhere to be found not even on the selvage. Plate blocks with trimmed selvage are worth considerably less than examples with the full selvage. I notice many blocks offered on eBay as plate blocks that are actually not. If you are a new collector that can place a large dent in your wallet! Here is an example: Shown below at left is a Scott #573 block that I have seen being offered as a plate block on many occasions. The correct terminology however would be: margin block of four with plate number. The correct configuration of a #573 plate block is a block of eight with two plate numbers and a guide arrow. An example of this is shown below at left. I know it seems that this is picky but it does mean a great difference in value ! Also, the placement of the plate number is crucial. On flat plate issues of the early half of the twentieth century that call for a plate number block of six, the number has to be on the center tab of the selvage or the block cannot be considered a plate block. The block would be considered a margin block of six with plate number. Again, a huge difference in value!

Here will be a brief lesson in some other terminology regarding multiples that are sometimes offered as plate blocks. Remember that these examples are NOT plate blocks and their respective value will differ.Below is shown just a common block of 4. Yes, I do see these offered as plate blocks quite frequently.

The block shown below is often offered as a plate block. Technically this is a margin block of four with plate number. Also, this issue would have to be in a block of six with the plate number in the center to qualify as a plate block.

The block shown below would be classified as a margin block of four with imprint and plate number.

The technical terminology for this block would be: margin block of four with plate number and imprint.

The block shown below would be know as a margin arrow block.

There are several more configurations.  I see items offered everyday as plate blocks when they are actually not and worth far less. It will pay to become familiar with the proper terminology to save you from making a costly mistake.