The Laboratory Manual Harmonisation Committee (LMHC) consists of representatives of the following renowned gemmological laboratories: AGTA-Gemological Testing Center (USA), CISGEM (Italy), GAAJ Laboratory (Japan), GIA-Gem Trade Laboratory (USA), GIT-Gem Testing Laboratory (Thailand), Gubelin Gem Lab (Switzerland), SSEF Swiss Gemmological Institute (Switzerland).

• LMHC Information Sheet #1
  
  Corundum with residue from the heating process present in healed fissures and/or cavities
  Members of the Laboratory Manual Harmonisation Committee (LMHC) have standardized the nomenclature that they use to describe heat treatment in corundum and the degree to which fissure "healing" has occurred, and thereside that remains within the healed fissures and cavities, following the heating of corundum.
  see attached pdf (245 KB)
  
  
  
• LMHC Information Sheet #2
  
  Corundum with colour induced by lattice diffusion
  Members of the Laboratory Manual Harmonisation Committee (LMHC) have standardised the nomenclature that they use to describe the lattice diffusion of elements into corundum.
  see attached pdf (59 KB)
  
  
  
• LMHC Information Sheet #3
  
  Corundum with glass filled fractures and/or cavities enhancing the clarity
  Members of the Laboratory Manual Harmonisation Committee (LMHC) have standardised the nomenclature that they use to describe filled fractures in corundum. This nomenclature is used for all situations that involve the filling of fractures or cavities with glass, where there are indications that the clarity of the gemstone has been altered by this process. Excluded from this nomenclature are treatments that involve the flux assisted healing of fractures (for which see Information Sheet #1).
  see attached pdf (199 KB)
  
  
  
• LMHC Information Sheet #4
  
  Padparadscha sapphire
  Members of the Laboratory Manual Harmonisation Committee (LMHC) have standardised the nomenclature that they use to describe a 'padparadscha sapphire'.
  see attached pdf (42 KB)

• LMHC Information Sheet #5
  
  Emerald - fissure filling / clarity enhancement
  Members of the Laboratory Manual Harmonisation Committee (LMHC) have standardised the nomenclature that they use to describe an emerald.
  see attached pdf (90 KB)

• LMHC Information Sheet #6
  
  Paraiba tourmaline
  Members of the Laboratory Manual Harmonisation Committee (LMHC) have standardised the nomenclature that they use to describe a Paraiba tourmaline.
  see attached pdf (55 KB)

• LMHC Information Sheet #7
  
  Corundum - No indications of heating and indications of heating
  Members of the Laboratory Manual Harmonisation Committee (LMHC) have standardised the nomenclature that they use to describe any corundum that shows no indications of heating or any corundum that shows indications of heating. See also Informations Sheets 1 to 4.
  see attached pdf (48 KB)