The patterns on these cards, as a consequence of the manufacturing processes, were trimmed slightly differently on top and bottom, resulting in uneven margins of 1/32 of an inch or less. She spent around a thousand hours, over four years, training herself to recognise the minute variations on particular cards. Sun figured out how she could leverage these differences that were almost imperceptible and acceptable by industry standards. She wasn't the first to recognise this vulnerability and capitalise on it. But she expanded on the strategy of exploiting unmatched trims, a ploy that has long been known as "edge sorting." Sun applied it to a baccarat spin-off called mini-baccarat and earned herself a nickname, the Queen of Sorts."
Sun used the technique to win $1 million from the Aria casino in 2011, and eventually brought Ivey into the fold.
"During the next year, he wired seven-figure sums to various casinos and did the betting. Sun did the edge-sorting of the cards and tipped off Ivey whether to wager on banker or player. Their combined winnings in Atlantic City, London and other places were in the eight figures."
In 2012, Ivey won more than $10 million in a London casino by edge-sorting, but he was refused payment as the casino claimed he was cheating. Ivey sued, but eventually lost the case.
"What this ruling says is a player is prohibited from combining his skill and intellect and visual acuity to beat the casino at its own game," [Ivey's lawyer] said, adding Ivey will appeal the ruling soon. "The casino agreed to every single accommodation requested by Phil Ivey in his four visits because they were eager to try to win his money."
