Which of the following is NOT a significance of grading tests?

Determining soil color is not considered a significance of grading tests. Grading tests primarily focus on analyzing the physical characteristics of the soil, such as its particle size distribution, which directly influences its engineering properties.

The measurement of permeability is vital as it provides insight into how water flows through the soil, which is essential for various engineering applications, including drainage and foundation design. Grading also gives detailed information about the particle size distribution, which is crucial for understanding the compactness and structural integrity of the soil.

Additionally, grading tests can indirectly assess the potential cohesion of soil; soils with certain gradation patterns can exhibit specific cohesive properties which are significant for stability and load-bearing capacity. However, color does not reveal valuable engineering properties related to soil behavior under load, water movement, or compaction and therefore is not a critical aspect assessed by grading tests.