The word "gertner" is a rare surname that can be tricky to spell for non-native speakers. Its IPA phonetic transcription is /ˈɡɜːtnər/. The sound "er" at the end is pronounced as the "ur" in "blur". The "g" is pronounced as in "goat", and the "t" as in "tune". The emphasized syllable is the second one, sounding like "turn". Although the pronunciation may vary slightly depending on the speaker's accent, this phonetic transcription should help you spell out "gertner" correctly.