Greth or Greith: How To spell?

The word Greth is misspelled against Greith, a verb meaning "To make ready; -- often used reflexively."

Word contains consecutive vowels 'EI' in between alphabets gr & th is misspelled as 'E' as letter 'I' is phonetically ignored
Wrong Spelling:  gr-e-th 
Correct Spelling:  gr-ei-th 
Explore spell check of Greith to spell without errors.