Grades of non-coking coals are defined on the basis of a gross calorific value of coal
In India coal is categorized into three classes:
1) Non-coking coal
2) Coking Coal
3) Semi coking and weakly coking coal

grading of non-coking coal as below:

Grade Gross calorific value in Kcal/Kg
A 6200 and more
B 5600 to 6200
C 4940 to 5600
D 4200 to 4940
E 3360 to 4200
F 2400 to 3360
G 1300 to 2400

Grades of coking coal are defined on the basis of ash content in the coal as below:

Grade Ash content
Steel grade 1 Less than 15%
Steel grade 2 15 to 18 %
Washery grade 1 18 to 21 %
Washery grade 2 21 to 24 %
Washery grade 3 24 to 28 %
Washery grade 4 28 to 35 %

Grades of Semi coking and weakly coking coals are defined on the basis of ash and moisture content in coal as below:

Grade Ash + Moisture
Grade 1 Less than 19%
Grade 2 19 to 24 %

URL: https://marcepinc.com/blog/grades-of-coal-in-india

Author's Bio: 

Marcep Inc. is a division of Marcep Group which has a JV with some of the major projects over the world and has entered the Asian market in sharing knowledge to the industry.