We quantify the quality of diamond films by a ratio of intensities of Raman shift peaks corresponding to diamond to non-diamond (graphitic) deposition during CVD growth of diamond films. Please see the following articles for the equation&methods used for assessing the diamond quality, in other words percentages of unwanted graphite in CVD grown diamonds:
1. Microscopic properties of MPCVD diamond coatings studied by micro-Raman and micro-photoluminescence spectroscopy, Kalyan S. Pal, Awadesh K. Mallik, Nandadulal Dandapat, Nihar R. Ray, Someswar Datta, SandipBysakh and Bichitra K. Guha, Bull. Mater. Sci., Vol. 38, No. 2, April 2015, pp. 537–549
2. Growth of 4” diameter polycrystalline diamond wafers with high thermal conductivity by 915 MHz microwave plasma chemical vapour deposition, A.F. Popovich, V.G. Ralchenko, V.K. Balla, A.K. Mallik, A.A. Khomich, A.P. Bolshakov, D.N. Sovyk, E.E. Ashkinazi, V.Yu. Yurov, Plasma Science and Technology, 19, 035503, 2017, https://doi.org/10.1088/2058-6272/19/3/035503.
3. Property mapping of polycrystalline diamond coatings over large area,Awadesh Kumar Mallik*, SandipBysakh, MonjoySreemany, Sudakshina Roy, JitenGhosh, Soumyendu Roy, Joana Catarina Mendes, Jose Gracio, Someswar Datta, Journal of Advanced Ceramics, 3(1), 2014, pp.56-70. doi: 10.1007/s40145-014-0093-1
XPS is not a convincing method to quantify graphite due to overlapping of carbon phases in and around 284 eV.
The Raman spectroscopy is the easy technique to assess the quality of synthetic CVD diamond and the percentage of sp3 (diamond) and sp2 (non-diamond/graphite) components. For details see the paper M.A. Nitti, G. Cicala et al Diamond & Related Materials 20 (2011) 221–226 and therein refs.
In your question you say quantify - Raman is qualative. If you want a quantitative technique you need to look at EELS or NEXAFS. Comapring the peak intensities in Raman is not quantitative obviosuly.