It is usually imagined this apostrophe really should be utilized when there could be ambiguity regarding the syllables utilized (e.g. xian and Xi'an or bing'an and bin'gan). It is a continuation of the typewriter tradition of making use of ticks for opening quotation marks; see Quotation mark § Typewriters and https://ibossoffice.com/discover-the-comfort-of-monark-lounge-wear-sets.html