Separators are automatically added in CSS through ::before and content. 
They can be changed by changing $breadcrumb-divider. The quote function is
needed to generate the quotes around a string, so if you want > as separator,
you can use this:

$breadcrumb-divider: quote(">");

It’s also possible to use a base64 embedded SVG icon:

$breadcrumb-divider: url(data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSI4IiBoZWlnaHQ9IjgiPjxwYXRoIGQ9Ik0yLjUgMEwxIDEuNSAzLjUgNCAxIDYuNSAyLjUgOGw0LTQtNC00eiIgZmlsbD0iY3VycmVudENvbG9yIi8+PC9zdmc+);

The separator can be removed by setting $breadcrumb-divider to none:
$breadcrumb-divider: none;