Matching up kitchen tile grouting colour for repair purposes?

Hello, can someone please help me?  When my kitchen was decorated a few years ago, the newly fitted kitchen wall tiles were grouted in a beigey sort of colour..... I cannot remember where the coloured grout was purchased or whether a white grout was tinted with a colour of some sort????  The problem I now have is that the majority of the tile grout is still perfect but some of it (mainly where the kettle is boiled) has literally cracked and has fallen out at some point  with the same colour as the and I would like to repair the missing grout areas???? I have searched on the internet and the only idea that I have found is to tint a white grout powder with a colour of some sort??? Is there a better way to do this or is this the best way forward and what sort/type of colourant/tint/colour should I chose in order to blend the finished result to the beigey colour that I want (I want to achieve the exact same colour as the original????)  Perhaps there is a professional out there who can advise me as to the best and easiest way to achieve this result???  Many, many thanks for any help that anyone who reads this can gibe me???? (Please)