Custom Field Values

-- HikaShop version -- : 4.0.1
-- Joomla version -- : 3.9.1
-- PHP version -- : 7.1.18

Im working on a site for someone who does custom items. Most of the time a chareteristic will work just fine, but there are a few instances that it won't work with.

The customer needs to be able to select mutltiple gem colors and then be charged for each gem color they choose. I would rather not have to duplicate 5 charectoristics on one product. However, if I go into custom fields where the user can use a checkbox to choose multiple colors, it doesn't have the option to charge them per selection.

Is there a way around this, because except for this one instance, I love Hikashop and would rather not have to switch to another ecommerce option.

Here is the problem with using the characteristics options...

My client has a bracelet, that when chosen, a person can add up to 5 birthstones onto it. While the first birthstone is free, each time an additional birthstone is added, it is $5/additional birthstone.

I can't create one characteristic and then just add it 5 times, so then I'd have to duplicate the same characteristic 5 TIMES. ie Birthstone 2, Birthstone 3, etc...

What I want to know is if there is a better way to do this, one that relies on customer input but will still add a dollar amount to the specified input?