Samples were prepared using standard petrological
techniques (polishing with a diamond-impregnated
scaife for the diamonds, polishing with SiC and diamond
suspension for all other samples). Raman spectra and
maps were obtained using a Thermo Scientific™ DXR™
Raman microscope. A 532 nm laser providing between
3 and 8 mW at the sample surface was used to obtain all
spectra. Reflected and transmitted light optics were used
to select analysis locations. Point spectra were collected
for between 20 and 50s depending on the sample. The
map was obtained in confocal mode using a 25 μm
pinhole to limit the unwanted signal from the surrounding
diamond; spectra (50s each) were obtained from a grid of
points spaced 2 μm apart, resulting in a total acquisition
time of ~13 hours. Because the mapped inclusion was at
a depth of ~100 μm in the diamond, a 50× long working
distance objective lens was used to prevent contact
between the diamond and the lens whilst maintaining
high spatial resolution