Printed Surfaces

Generally Air-India coasters have the identical design and colour combination printed on both sides. These are called 1/2 Printing. Another way of saying this is that 1 design is printed on 2 surfaces, hence 1/2. This is the most common type of coaster available, and it seems that this was the desired state of the design.
 
However, there are many Air-India Coasters with 1 design printed on only 1 surface, and the other surface is blank. These are called 1/1 Printing, and are collectable additionally as a variety.
 
Then you have 2 designs, printed on 2 sides. This means that each side has a different design. These are called 2/2 Printing. So far, I have come across only one such example.
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Printed 1/2

Air-India Abu dhabi coaster

Example of Type 1.1 design Printed 1/2 (same design on both sides)

Example of Type 1.2 design Printed 1/2 (same design on both sides)

Example of Type 2 design Printed 1/2 (same design on both sides)

Example of Type 3 design Printed 1/2 (same design on both sides)

Example of Type 4.1 design Printed 1/2 (same design on both sides)

There is no example of Type 4.2 design printed 1/2. This series was only issued as printed 1/1 (uniface).

Example of Type 5 design Printed 1/2 (same design on both sides)

There is no example of Type 6 printed 1/2

Printed 2/2 - Highly unusual

There are many examples of Coasters with different designs printed on opposite surfaces (called 2/2 printing), but Air-India does not seem to use this method.

Over 80% of the Air-India coasters have the same design on both surfaces (called 1/2 printing), which is shown above, and the remaining are with a design on one surface, and are plain on the opposing surface (called 1/1 printing). So far, I have come across only one example of a coaster with different designs on opposing surfaces (called 2/2 printing). This is a Type 4.1 coaster with Bahrain on one side, and Bangkok on the other.
Logically one would conclude that this is an error, since it is an unusual find, which I got from an advanced collector, and despite having looked around, have not come across another example.
The interesting thing about these two coasters is that both have the same Pink + Ochre colour combination, and the city names follow each other in sequence when arranged alphabetically. I wonder if this had anything to do with it.

Left: The Bahrain design on one side of this Type 4.1 coaster.
Right: The Bangkok design on the opposite surface of the same item.