How to create this gamma symbol

Question

How do I create this gamma symbol?

Answer 1

A Gamma is an upside down L:

\documentclass{article}
\usepackage{amssymb,graphicx}

\newcommand{\bbGamma}{{\mathpalette\makebbGamma\relax}}
\newcommand{\makebbGamma}[2]{%
  \raisebox{\depth}{\scalebox{1}[-1]{$\mathsurround=0pt#1\mathbb{L}$}}%
}

\begin{document}

$\Gamma\bbGamma \mathrm{L}\mathbb{L}$

\end{document}

Answer 2

You could use the package https://ctan.org/pkg/unicode-math and choose a math font. That way you get a concise set of glyphs (as long as the typeface's designer did their job well). You should also consider https://ctan.org/pkg/fontspec for a coherent use of typefaces in math mode and text mode. The following examples generate serif blackboard bold capital gammas.

The following glyphs should all be the same (and they look alike to me).

\documentclass{memoir}
\usepackage{amsmath}

\usepackage{unicode-math}
\setmathfont{Asana Math}

\begin{document}
$\BbbGamma \mathbb{\Gamma} \mathbb{Γ} \symbb{\Gamma} \symbb{Γ} ℾ \symbol{"213E}$
\end{document}

---

EDIT: You can also apply egreg's solution to another underrated font which blends well with CM and LM, please compare them yourself:

\documentclass[landscape]{memoir}
\usepackage{amsmath}
\usepackage{graphicx,dsfont,amssymb,booktabs}

\newcommand\BbbGamma{\reflectbox{\rotatebox[origin=c]{180}{$\mathds L$}}}
\newcommand\BbbGammaVar{\reflectbox{\rotatebox[origin=c]{180}{$\mathbb L$}}}

\begin{document}
\begin{tabular}{*{16}{>{$}c<{$}} }
    \toprule
    \BbbGamma & \mathds h & \mathds k & \mathds 1 & \mathds A & \mathds B & \mathds C & \mathds D & \mathds E & \mathds F & \mathds G & \mathds H & \mathds I & \mathds J & \mathds K \\
    \Gamma & \text h & \text k & \text 1 & \text A & \text B & \text C & \text D & \text E & \text F & \text G & \text H & \text I & \text J & \text K \\
    \BbbGammaVar & \mathbb h & \mathbb k & \mathbb 1 & \mathbb A & \mathbb B & \mathbb C & \mathbb D & \mathbb E & \mathbb F & \mathbb G & \mathbb H & \mathbb I & \mathbb J & \mathbb K \\
    \midrule
    \mathds L & \mathds M & \mathds N & \mathds O & \mathds P & \mathds Q & \mathds R & \mathds S & \mathds T & \mathds U & \mathds V & \mathds W & \mathds X & \mathds Y & \mathds Z \\
    \text L & \text M & \text N & \text O & \text P & \text Q & \text R & \text S & \text T & \text U & \text V & \text W & \text X & \text Y & \text Z \\ 
    \mathbb L & \mathbb M & \mathbb N & \mathbb O & \mathbb P & \mathbb Q & \mathbb R & \mathbb S & \mathbb T & \mathbb U & \mathbb V & \mathbb W & \mathbb X & \mathbb Y & \mathbb Z \\ 
    \bottomrule
\end{tabular}
\end{document}

Top row: \mathds, middle row: Latin Modern, bottom row: \mathbb. My understanding is that \mathds is actually much closer to what someone would expect from a blackboard bold by just add a single double stroke on a blackboard than \mathbb.

---

The website https://www.fileformat.info/info/unicode/char/213e/fontsupport.htm# gives a comparison of various typefaces.

Answer 3

WARNING: Some long time ago there was some package for this, I do not remember the details. I guess it was somehow related to this thingy. And I cannot really tell you why this was dropped, perhaps this discussion helps you.

Anyway, I kept excerpts of this on my machine and usually do something like this

\documentclass{article}
\newcommand{\bbfamily}{\fontencoding{U}\fontfamily{bbold}\selectfont}
\DeclareMathAlphabet{\mathbb}{U}{bbold}{m}{n}
\DeclareSymbolFont{bbold}{U}{bbold}{m}{n}
\SetSymbolFont{bbold}{bold}{U}{bbold}{m}{n}
\DeclareMathSymbol{\bbGamma}{\mathord}{bbold}{'000}
\DeclareMathSymbol{\bbDelta}{\mathord}{bbold}{'001}
\DeclareMathSymbol{\bbVarTheta}{\mathord}{bbold}{'002}
\DeclareMathSymbol{\bbLambda}{\mathord}{bbold}{'003}
\DeclareMathSymbol{\bbTheta}{\mathord}{bbold}{'004}
\DeclareMathSymbol{\bbPi}{\mathord}{bbold}{'005}
\DeclareMathSymbol{\bbSigma}{\mathord}{bbold}{'006}
\DeclareMathSymbol{\bbUpsilon}{\mathord}{bbold}{'007}
\DeclareMathSymbol{\bbPhi}{\mathord}{bbold}{'010}
\DeclareMathSymbol{\bbPsi}{\mathord}{bbold}{'011}
\DeclareMathSymbol{\bbOmega}{\mathord}{bbold}{'012}
\DeclareMathSymbol{\bbalpha}{\mathord}{bbold}{"0B}
\DeclareMathSymbol{\bbbeta}{\mathord}{bbold}{"0C}
\DeclareMathSymbol{\bbgamma}{\mathord}{bbold}{"0D}
\DeclareMathSymbol{\bbdelta}{\mathord}{bbold}{"0E}
\DeclareMathSymbol{\bbespilon}{\mathord}{bbold}{"0F}
\DeclareMathSymbol{\bbzeta}{\mathord}{bbold}{"10}
\DeclareMathSymbol{\bbeta}{\mathord}{bbold}{"11}
\DeclareMathSymbol{\bbtheta}{\mathord}{bbold}{"12}
\DeclareMathSymbol{\bbiota}{\mathord}{bbold}{"13}
\DeclareMathSymbol{\bbkappa}{\mathord}{bbold}{"14}
\DeclareMathSymbol{\bblambda}{\mathord}{bbold}{"15}
\DeclareMathSymbol{\bbmu}{\mathord}{bbold}{"16}
\DeclareMathSymbol{\bbnu}{\mathord}{bbold}{"17}
\DeclareMathSymbol{\bbxi}{\mathord}{bbold}{"18}
\DeclareMathSymbol{\bbpi}{\mathord}{bbold}{"19}
\DeclareMathSymbol{\bbrho}{\mathord}{bbold}{"1A}
\DeclareMathSymbol{\bbsigma}{\mathord}{bbold}{"1B}
\DeclareMathSymbol{\bbtau}{\mathord}{bbold}{"1C}
\DeclareMathSymbol{\bbupsilon}{\mathord}{bbold}{"1D}
\DeclareMathSymbol{\bbphi}{\mathord}{bbold}{"1E}
\DeclareMathSymbol{\bbchi}{\mathord}{bbold}{"1F}
\DeclareMathSymbol{\bbpsi}{\mathord}{bbold}{"20}
\DeclareMathSymbol{\bbomega}{\mathord}{bbold}{"7F}
\DeclareMathSymbol{\bbell}{\mathord}{bbold}{"40}
\newcommand{\BBsymbol}[1]{%
\ifcat#1a\mathbbm{#1}\else
    \ifx#1\Gamma\bbGamma\fi
    \ifx#1\Delta\bbDelta\fi
    \ifx#1\VarTheta\bbVarTheta\fi
    \ifx#1\Lambda\bbLambda\fi
    \ifx#1\Theta\bbTheta\fi
    \ifx#1\Pi\bbPi\fi
    \ifx#1\Sigma\bbSigma\fi
    \ifx#1\Upsilon\bbUpsilon\fi
    \ifx#1\Phi\bbPhi\fi
    \ifx#1\Psi\bbPsi\fi
    \ifx#1\Omega\bbOmega\fi
    \ifx#1\alpha\bbalpha\fi
    \ifx#1\beta\bbbeta\fi
    \ifx#1\gamma\bbgamma\fi
    \ifx#1\delta\bbdelta\fi
    \ifx#1\espilon\bbespilon\fi
    \ifx#1\zeta\bbzeta\fi
    \ifx#1\eta\bbeta\fi
    \ifx#1\theta\bbtheta\fi
    \ifx#1\iota\bbiota\fi
    \ifx#1\kappa\bbkappa\fi
    \ifx#1\lambda\bblambda\fi
    \ifx#1\mu\bbmu\fi
    \ifx#1\nu\bbnu\fi
    \ifx#1\xi\bbxi\fi
    \ifx#1\pi\bbpi\fi
    \ifx#1\rho\bbrho\fi
    \ifx#1\sigma\bbsigma\fi
    \ifx#1\tau\bbtau\fi
    \ifx#1\upsilon\bbupsilon\fi
    \ifx#1\phi\bbphi\fi
    \ifx#1\chi\bbchi\fi
    \ifx#1\psi\bbpsi\fi
    \ifx#1\omega\bbomega\fi
    \ifx#1\ell\bbell\fi
\fi
}

\begin{document}
$\BBsymbol{\Gamma}\BBsymbol{\alpha}$
\end{document}

And of course the outcome is not as nice as in egreg's answer but here you have double stroke letters for all Greek letters. (And those who feel like they need to shout at me: this post starts with a big disclaimer... ;-)

Answer 4

I recommend unicode-math for new documents, as CampanIgnis already posted. There are several different packages that support double-struck blackboard-bold Greek letters for legacy NFSS, including:

\documentclass[varwidth, preview]{standalone}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[bbgreekl]{mathbbol}

\begin{document}
\( \mathbb{\Gamma} \)
\end{document}

Other packages including these symbols are stix and mbboard.

Answer 5

this works as well:

\documentclass{standalone}

\newcommand\mygamma{$\mathrm{I} \hspace{-0.4ex} \Gamma$}

\begin{document}

\tiny \mygamma
\small \mygamma
\normalsize \mygamma
\large \mygamma
\Large \mygamma
\Huge \mygamma

\end{document}

produces this result:

it works also with other letters, e.g. R or N (real or natural numbers):

\newcommand\myr{$\mathrm{I} \hspace{-0.4ex} \mathrm{R}$}
\newcommand\myn{$\mathrm{I} \hspace{-0.4ex} \mathrm{N}$}

Answer 6

I also like the contour package

\documentclass[a4paper,12pt]{article}
\usepackage[outline]{contour}
\newcommand*{\fancy}[1]{\color{white}\contour{black}{#1}}
\begin{document}
\fancy{$\Gamma$}
\end{document}