Engineers use the abbreviation MM to denote million. MMkcal is simply one million kilocalories. This is also commonly abbreviated as Gcal (as in giga calories).
'Finest' is a judgement call, and you are the judge. Lab-created diamonds can be custom-ordered, based on the source of the carbon. You can also specify a colour of diamond that you want. Any lab-created diamond will always be a lab-created diamond, and its competitor won't be another lab-created diamond, but will be a natural diamond.