It used to be 100,000 tier points, but I think they are using a different system now that makes it up to the player's "home" casino how they offer 7* even if someone qualifies with points.

The tier levels with Harrahs are much different than what you may be used to with the airlines. While there are some hard benefits that kick in with each level, the real benefits are all based on your ADT (avg daily theoretical loss). This number is what determines your soft benefits such as free flights, cash, suites, etc.

In my opinion, the best of both worlds is to keep a decent ADT as a low Diamond. You really don't benefit from getting much over 11,000 tier points especially if you are gambling low amounts over several days. For example, if you stop by your local Harrah's casino on your way home from work a couple days a week and rack up 200 tier points per visit, you'll end up the year as a Diamond but you'll have a low ADT and your offers will not be earth shattering. Now, if you make 3 or 4 weekend trips to an out of town casino per year and drop 1000 tier points per day, then you'll be a low Diamond (11,000-15,000 points), but your ADT will be decent and you'll get some nice offers. I'm part of that 2nd group and we get free rooms pretty much any day of the year with $300-$500 per trip in incentives (travel cash, gifts, tournaments, etc) plus another $300-$500 in comps.