Choose Black Granite

When choosing between pink granite and black granite for precision measurement in manufacturing, black granite is generally the superior choice for high-precision applications, including metrology and manufacturing inspection. Here’s why:

Property	Black Granite	Pink Granite
Density	Higher (less porous)	Lower (more porous)
Hardness	Harder, more wear-resistant	Softer, wears faster
Stability	Less affected by temperature changes	More affected to temperature fluctuations
Absorption	Lower moisture absorption	Higher moisture absorption
Flatness Retention	Maintains flatness longer	More prone to warping over time
Preferred Use	High-precision metrology (Grade AA, A)	General machining / inspection (Grade B)

2. Why Black Granite is Better for Precision Measurement?

More Stable and Less Porous – Absorbs less moisture, which helps maintain flatness and prevents expansion due to humidity.
Higher Hardness – Wears more slowly, extending the life of the surface plate.
Lower Thermal Expansion – More resistant to temperature-induced distortions.
Greater Accuracy Retention – Holds its calibration and precision longer, making it ideal for medical equipment, aerospace, and precision machining.

3. When to Use Pink Granite?

Lower-cost applications where ultra-high precision is not required.
General inspection and layout work in machine shops.
Larger, less frequently used plates, where cost is a bigger concern than ultimate precision.
Conclusion: Choose Black Granite for High-Precision Needs

If your goal is precision measurement in manufacturing, especially for medical equipment, black granite (Grade AA or A) is the better choice due to its durability, stability, and accuracy retention.