Among Chaldean numerologists, there are two common ways to pronounce the term “Chaldean”. The letters “ch” can be pronounced either like in the word chemistry or like in church. For example, Lloyd Strayhorn and Anmarie Uber pronounce Chaldean as /kælˈdiːən/. On the other hand, August Darius Danielsson, Johannes and Estel Ehwas, and many other numerologists pronounce it as /tʃælˈdiːən/.
The Akkadians referred to the Chaldeans as Kaldu or Kašdu, which led to the Greek term Χαλδαία (Khaldaía) and then to the Latin version Chaldaea. From this root, various European languages developed their own versions of the name, such as Caldea in Italian and Spanish, Caldeia in Portuguese, Chaldäa in German, Chaldée in French, Халдеи in Russian, and Chaldea (/kælˈdiːə/) in English.
Therefore, in the English language, the name Chaldean numerology should be pronounced as Lloyd Strayhorn and Anmarie Uber do: /kælˈdiːən/!
The Mystery of Numbers, Luck, Worlds and Planets 