italic small caps in Garamond #3?

Question

I have the OTF files for Garamond #3 LT Pro, supplied by my publisher. I need to use italic small caps. The following MWE:

\documentclass{article}

\usepackage{fontspec}
\setmainfont{Garamond3LTPro}[
  Extension = .otf ,
  BoldFont = *-Bold ,
  ItalicFont = *-Italic ,
  BoldItalicFont = *-BoldItalic ]

\fontspec{Garamond3LTPro-Italic.otf}[Letters=SmallCaps]

\begin{document}
\end{document}

produces the following output:

*************************************************
* fontspec warning: "icu-feature-not-exist-in-font"
* 
* OpenType feature 'Letters=SmallCaps' (+smcp) not available for font
* 'Garamond3LTPro-Italic.otf' with script 'Latin' and language 'Default'.
*************************************************

The publisher insists that Garamond #3 LT Pro Italic has a small caps. Is he wrong, and if so how can I prove it?

What makes me suspicious is that this page:

http://www.myfonts.com/fonts/linotype/garamond-3/pro-roman/specs.html

lists smcp among the tags, but this page:

http://www.myfonts.com/fonts/linotype/garamond-3/pro-italic/specs.html

does not.

The need for italic small caps is the following. French typography is fond of small caps, in particular for centuries for which roman numerals are used: {\scshape xviii}e siècle (not 18e siècle). In a bibliography, book titles are in italics, and, as we say in English, voilà. (Author names in bibliographies are also in sc, but upright, which Garamond 3 has).

Since my need is limited to a few century numbers in the bibliography (set in 9pt), I suppose that a fake it-sc would be good enough.

Answer 1

As you already know from myfonts.com, Garamond 3 has no small caps italics. I guess that your editor has been using «fake» small caps, which InDesign, LibreOffice or Word can produce. I strongly advise not to use them. Instead, you should try some «real» small caps from other Garamond versions. There are quite a few.

For instance, EB Garamond:

\documentclass[12pt]{article}
\usepackage{ebgaramond}
\usepackage{lipsum}
\begin{document}
\emph{\textsc{\lipsum[1]}}
\end{document}

Update

Italic small caps in roman numerals for centuries in French. NB. I added some space between the small caps and the superscript e, because it would look otherwise somewhat cramped.

\documentclass[12pt]{article}
\usepackage{ebgaramond}
\newcommand{\siecle}[1]{\emph{
    \textsc{#1}\kern.1em\textsuperscript{e}
    {siècle}}}
\begin{document}
    \siecle{xv}
    \siecle{xvi}
    \siecle{xvii}
    \siecle{xviii}
    \siecle{xix}
    \siecle{xx}
    \siecle{xxi}
\end{document}

Answer 2

Three high-quality commercial garaldes that feature small-cap italics are Sabon Next (by Tschichold and Porchez), Palatino nova (by Zapf and Kobayashi), and Garamond Premier Pro (by Slimbach (?)). Among these three fonts, GPP clearly is the most condensed, while Palatino is the least condensed. The Palatino italic shape is also the least slanted of the three.

\documentclass{article}
\usepackage{fontspec}
\begin{document}

\setmainfont{Sabon Next LT Pro}
\subsubsection*{Sabon Next LT Pro}
Le \textsc{xviii}\textsuperscript{e} siècle, 
\textit{le \textsc{xviii}\kern0.5pt\textsuperscript{e} siècle}


\setmainfont{Palatino nova}
\subsubsection*{Palatino nova}
Le \textsc{xviii}\textsuperscript{e} siècle, 
\textit{le \textsc{xviii}\kern0.5pt\textsuperscript{e} siècle}

\setmainfont[ItalicFont = Garamond Premier Pro Italic]{Garamond Premier Pro}
\subsubsection*{Garamond Premier Pro}
Le \textsc{xviii}\textsuperscript{e} siècle, 
\textit{le \textsc{xviii}\kern0.75pt\textsuperscript{e} siècle}

\end{document}