The 'unalterable loss' they refer to, is of course the genocide that occurred under the Pol Pot Regime in Cambodia between 1975 and 1979, resulting in the loss of between 1.7 to 2 million Cambodians (nearly a third of the population). As is often said, "every Cambodian was affected by the Khmer Rouge era". Phousera, born to a French mother and Cambodian father, was able to flee to France with his mother when the Khmer Rouge overtook Phnom Penh, thanks to foreign passports. Tragically, his father was not permitted exodus and lost his life before the culmination of violence.
Phousera has created a series of large urns to act as monuments to "retain the intimacy and humanity of a cremation ceremony," a critical practice in Buddhist death ceremony that was denied to Pol Pot's victims. Phousera says his urns are “for all these people who were not honoured in a proper way.” Both the beauty and the intention of the exhibit are striking and well worth a visit for those visiting Phnom Penh in the months ahead.
See this link for more info.
(Sadly, I hadn't packed my camera along today, so all images are iPhone quality.)