Special characters most of the time fail when the CSV is saved in an incorrect encoding format. Numerous Excel-exported CSV files are saved in ANSI, and if you process them with a simple CSV-to-VCF converter, characters like accents, emojis, and non-English letters are changed into question marks. I think half of my client list was the one that got messed up in the process of CSV to vCard conversion. What saved me was definitely saving the CSV in the UTF-8 format right away. In Excel or Google Sheets, you can select the option Save As UTF-8 CSV. After that, I did the CSV to VCF export once again, and this time all my files looked perfect. Moreover, some converters completely lack the support of advanced characters; that is why I decided to move to DataVare CSV to vCard Converter, which is a tool that keeps UTF-8 and does not separate or break symbols and emojis. I have not lost a single character in my files since then.