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The House point hourglasses are four giant hourglasses located in the Entrance Hall used to record the number of house points that have been awarded or deducted. There is one hourglass for each of the Hogwarts Houses: Gryffindor, Hufflepuff, Ravenclaw, and Slytherin. When points are earned some gems (depending on house colours) fall from the upper bulb into the lower. When points have been deducted, they do the opposite, retreating into the upper bulb. For example, when ten points are taken from Gryffindor, ten red gems will fall back into the upper half of the hourglass.
During Severus Snape's escape from Hogwarts after he killed Albus Dumbledore in 1997, a curse shattered the Gryffindor hourglass, causing red rubies to flood the floor like blood. The Slytherin hourglass was shattered in 1998 during the Battle of Hogwarts and green emeralds rolled across the floor. The two were probably repaired and remounted on the wall.
The Gryffindor, Ravenclaw, and Slytherin hourglasses contain rubies, sapphires, and emeralds, respectively. The Hufflepuff hourglasses contain a yellow gem, perhaps topaz.[1]
In Harry Potter and the Half-Blood Prince, when Severus Snape takes points from Harry after meeting him at the Hogwarts gates, he remarks that Gryffindor would be starting out in negative points. However, previously in Harry Potter and the Order of the Phoenix, Snape was unable to take any more points from Gryffindor when they had none left. McGonagall had to add points before any more could be removed.
The hourglasses are also featured at the entrance in the Hogwarts castle in The Wizarding World of Harry Potter. They show that Gryffindor is in the lead, Slytherin second, Hufflepuff third, and Ravenclaw last in achieving house points. Ironically, Ravenclaw students are famous because of their wisdom, creativity, and intelligence, some of the factors that apply to earning house points.
