Grab that cone with both hands between your thumbs and index fingers. Slowly, try to pull the bracts (petals) away from the center strig. The closer to ripeness the cone gets, the easier they will break away from the strig. Under-ripe cones tend to either tear the strig or the bracts won't come off without ripping. Determining ripeness takes a lot of practice for many folks and there's really no simple cut/dry test to say one way or another. This method was suggested to me by a guy who spent his life breeding hops so I tend to use it in conjunction with some other indicators. Tear away!