Starting with May 20th 2019, the definition of the kilogram will no longer be based by a lump in France.
It will now be based on the mass of an exact number of photons, or particles of light, with a particular wavelength.
Please also have a look at the wonderful movie https://de.wikipedia.org/wiki/1001_Gramm
https://www.engadget.com/2019/05/17/kilogram-definition-update-may-20/