Polycrystalline cubic crystal boron nitride and tool

A polycrystalline cubic boron nitride comprising:

• a cubic boron nitride particle group wherein
• the polycrystalline cubic boron nitride has a ratio of a second length to a first length of 0.99 or less,
• each of the first length and the second length is a value measured on a surface of the polycrystalline cubic boron nitride with an indentation formed by a Knoop hardness test under conditions specified in ISO4545-1 and ISO4545-4,
• the test force of the Knoop hardness test is 4.9 N,
• the second length represents the length of the longer diagonal of the indentation,
• the first length represents the sum of the second length and the length of a streaky indentation,
• the streaky indentation extends from both ends of the longer diagonal of the indentation toward the outside of the indentation,
• the length of the streaky indentation is measured by observing the surface of the polycrystalline cubic boron nitride with a field emission scanning electron microscope at a magnification of no less than 5000 times and no more than 10000 times, and
• the second length is measured by observing the surface of the polycrystalline cubic boron nitride with an optical microscope at a magnification of no less than 500 times and no more than 1000 times.