Point of sale system for jewelry store

This would be a POS for a jewelry store Programmer decides in what language would be best to do it in and would have to explain to me why they chose that language. I want to be able to run this app on Windows, Mac or Linux MVC format needed for whatever language you chose. You have 3 months to do this. I want an update every 3 days. On the first 10 days I want to see the design of the database and application design to give feedback and changes if needed all other information is in the doc I need everything done according to docs specifications. If you have better solutions I would like to hear them. Also, any doubts please contact me by chat. All words on screen need to be called from folder containing only words on screen. (in doc) -user manual -technical manual -application -databases get called from systems through mail or other way, you think of how to solve it without having to pay for a domain while keeping itself up to date as close to real time as posible (you would have to see the most convenient way to do this as I think mails would not work but this is something you need to think about). -mails for end of day reports and database backups. -Label printer -Label design -Scanner after half of it is done the first milestone gets released. At completion the full payment is released. I pay for what I have. first half CRUD reports database cash registers admin panel user panels owner panel all other specifications in the doc outside of bottom second half. second half database updating in almost realtime label printer scanner technical manual user manual