'Gamma' and 'ion' sound like contents of a physics textbook. But here, we are looking at a symbol with an even deeper meaning
The Gammadion Cross is formed by group of four Greek letter gamma (Γ), the capitalised third letter of the Greek alphabet.
In a Christian context, 'three' is a reminder of the Trinity, and each gamma represents one of the four Evangelists, radiating from the central Greek Cross, which represents Christ.
The most common layout is as a Swastika Cross but other arrangements exist, such as the cross shown on the right. This is a Voided Cross and similar to the relatively recent Thugsta Cross.
Alternative names include Gamma Cross and Gammata Cross.