Diamond
From Astrowiki-en
Astrological term for the perihelion, the point in the Earth's orbit at which it is closest to the Sun. From a geocentric point of view, this is the point at which the Sun is closest to the Earth. The corresponding opposite point is the Black Sun, the term used to describe the aphelion and point of greatest distance between Sun and Earth.
The diamond has virtually no significance in astrological interpretation.