Natural decorative stone is made by processing natural stone, and its quality depends on the quality of the raw materials and the processing process. Poor quality marble and granite slabs typically exhibit the following characteristics:

The surface pattern color tone of high-quality stone is not aesthetically pleasing. The surface pattern color of high-quality stone is beautiful and generous, giving people a noble and elegant feeling, making the decoration effect even more outstanding. After processing, the surface patterns and tones of inferior stone materials are not aesthetically pleasing and cannot provide aesthetic enjoyment. Therefore, the color tone of surface patterns is one of the main indicators for evaluating the quality of stone materials.
The appearance quality of the processed board is poor, and there may be some appearance defects during the stone processing process. If these appearance defects exceed the range specified by national standards, then the stone is considered unqualified. Using inferior stone materials with poor appearance quality for decoration can lead to poor overall effect. Therefore, when evaluating the quality of stone materials, in addition to considering the color of the patterns, it is also necessary to check their appearance quality.
The stone used for decoration with significant deviation in specifications and dimensions is usually processed into boards and constructed by splicing or pasting. If there is a significant deviation in the specifications and dimensions of the board, the surface after laying will appear uneven, with uneven joints, especially during facade decoration, which can lead to uneven lines on the decorative surface and affect the overall decoration effect. Therefore, deviations in specifications and dimensions can directly affect the decorative effect of stone materials.
The physical and chemical performance indicators are poor, and the compressive strength, flexural strength, wear resistance, durability, and hardness of inferior stone materials are all poor, which cannot guarantee the service life of the stone.
To identify inferior marble and granite slabs, the following methods can be used:

Observing the surface pattern and color tone: Carefully observe the surface pattern of the stone, and the pattern color of high-quality stone is usually beautiful and generous.
Check the appearance quality: Check whether there are obvious appearance defects on the surface of the board, such as cracks, damages, etc. At the same time, it is necessary to ensure that the appearance defects do not exceed the scope specified by national standards.
Measurement of specifications and dimensions: Measure the specifications and dimensions of the board to ensure that it meets the decorative design requirements, and pay attention to avoiding excessive size deviations.
Physical and chemical performance testing: Through laboratory testing, the compressive strength, flexural strength, wear resistance and other physical and chemical performance indicators of stone materials are tested to ensure that they meet the requirements of relevant standards.
By using the above methods, it is possible to effectively identify inferior marble and granite slabs, select high-quality stones for decoration, and improve the decorative effect and service life.