I parked at the far end of the road, though it is possible to park at the pullout/trailhead 1/2-mile or so earlier. The only other vehicle that far up was a Prius, which I admit surprised me, but I myself was in an Outback, so whatever.
I did not identify a spur to the summit so I continued on to the other candidate 3000' to the northwest. Continuing back, and checking Gaia, I could not find a trail, so I bushwhacked it. After about 1/4-1/2 mile I did run into a trail that faded in and out here and there, with the occasional downed tree across the trail. The benchmark is about 20 yards in front of the weather station.
I followed the spur on the way down until it reconnected with the trail. Taking a look back from the trail, it was even more apparent that the spur to the summit is not readily identified from the main trail. Be prepared to look for it or do a little bushwhacking.
Jaunted up this little hill while out on a nice hike with my wife and kiddo. Great views.
Short and easy.
First I picked off the Franklin county highpoint, then it was on to Tekoa Mtn (Whitman County), then Ray Ridge's HP for Asotin county, and finally Diamond Peak and the two other spots. After that, I drove down to the Eagle Cap TH and spent the night before doing Eagle Cap the next morning.
It was a blur of a day.
Some COHP.org trip reports can be found HERE.
I summited Diamond Peak (and the other Garfield County candidates) in the middle of a long day in which I first summited Oregon Butte and last summited the Asotin County highpoint candidates. Garfield County was my 15th WA COHP.