"Honest as a Huguenot" was as proverbial in the seventeenth century as the respect for law of the Dutch which Sir. W. Temple admired, and, a century later, that of the English as compared with those Continental peoples that had not been through this ethical schooling.
Loraine Boettner, The Reformed Doctrine of Predestination, p. 376:
The Huguenots made up the industrious artisan class of France and to be "honest as a Huguenot" became a proverb, denoting the highest degree of integrity.
Nathaniel MacFetridge, Calvinism in History, p. 123:
Outside of the circle of the Huguenots there was indeed but little that deserved the name of morality in France. Their honesty was so remarkable that even among their bitterest enemies it was proverbial. To be "honest as a Huguenot" was deemed the highest degree of integrity. And while they were stigmatized by the Roman Catholics as "heretics," "atheists," "blasphemers," "monsters vomited forth of hell," and the like, not one accusation was brought against the morality and integrity of their character. "The silence of their enemies on this head is," says Smiles, "perhaps the most eloquent testimony in their favor."
Samuel Smiles, The Huguenots: Their Settlements, Churches, and Industries in England and Ireland, pp. 134-135:
The Huguenot's word was as good as his bond, and to "honest as a Huguenot" passed into a proverb. This quality of integrity -- which is essential in the merchant who deals with foreigners whom he never sees -- so characterized the business transactions of the Huguenots, that the foreign trade of the country fell almost entirely into their hands.
William Maxwell Blackburn, Admiral Coligny, and the Rise of the Huguenots, p. 189:
"Honest as a Huguenot" was the proverb coined in his honour, and made current through long generations. As a neighbour, he was just and truthful; as a civilian, rare in his integrity and observance of law; as an artisan or a tradesman, he attended to his own affairs, and his goods had their value upon their very face; as an official he could be trusted with untold gold, and happy was the Pharoah who had such a Joseph at court. When Romanist noble or king wished for an honest man, to whom he could entrust life and property, he drew into his service a Huguenot. Even Charles IX. retained, to the last hour of his life, the old Huguenot nurse who had rocked his cradle, and he would have no other physician than Ambrose Pare, the chosen surgeon of his grandfather. Among all the Italian poisoners, Catherine knew that her children were safe when such a man dealt out the medicines. And she, too, must have her Huguenot ladies to succeed the trustworthy Madame de Chatillon and Madame de Roye. She long felt safest when Coligny was at the court. This compliment to Huguenot integrity was paid everywhere, down to the latest times.