Summer sun ring was removed from RuneScape after an update, but still exists in-game for those who had obtained it.
Summer sun ring is an item that was available from the Squeal of Fortune throughout the summer months. It originally had stats, but they were removed in 2013, making it a purely cosmetic item. It is meant to portray a positive mood, while its counterpart, the Summer storm ring portrays a negative mood.
When equipped, the ring makes a unique sound and can be right-clicked to activate an emote. When the emote is performed a miniature sun appears above the player's head. This does not work when under a roof (including POHs); however there are some exceptions, including the area outside Kuradal's dungeon. The sun does not follow the player and simply stays in the space it was spawned. The sun lasts approximately 20 seconds, and the player must wait a further 20 seconds to activate the Summer sun ring again. This cooldown is shared with the Summer storm ring.
When attempting to activate the ring in a building, a chatbox message states, "You can't use the ring while you are under a roof." It doesn't work in some roofless buildings, like some houses in Burgh de Rott.