# How to get bold version of blackboard bold fonts?

Right now, I have \mathbb{C} and \boldsymbol{\mathbb{C}} both producing the same character. What package/command do I need to get a bolder character?

In the modern toolchain with unicode-math, \boldsymbol\mathbb works if you load a math font with a bold version (as of July 2019, XITS Math, Libertinus Math or Minion Math) or if you manually load a bold math font with, for example, \setmathfont[version=bold]{Minion Math Semibold}.

Otherwise, as Sebastiano beat me to saying, load mathalpha (formerly mathalfa) with a double-struck font that comes in bold (such as [bb=px]) and use its \mathbbb.

Here there is my proposal as an alternative. You could to use bb = boondox + mathalpha (as suggest by the user @Davislor - see comment and your nice answer), but it changes the nature of the symbol. You have always the bold.

Here there is a little code

\documentclass[a4paper,12pt]{article}
\usepackage[bb = boondox]{mathalpha}
\begin{document}
$\mathbb{R}, \mathbbb{R}, \mathbbb{Z}$
\end{document}


and a screenshot:

• Note that the package has been renamed mathalpha. – Davislor Jul 15 '19 at 20:03
• @Davislor I didn't know and thank you very much. Then in my book I change it, because I use this name. – Sebastiano Jul 15 '19 at 20:05
• It might still be a good idea to use mathalfa in our examples for a while, because that’s still supported for backward-compatibility and it might take a while for everyone to update. – Davislor Jul 15 '19 at 20:06