Although little is known about the Genuese variety they used to grow, Volkamer indicated that it was very similar (besides the taste in which the Genuese was reported to be not as good) to the one illustrated by him as well as by Ferrari as the Cedro Ordinario, and they seem to be very close in nature and form to the Diamante of today.
Most adherent to the Diamante variety of Calabria are still the Chabad's who's late Rabbi's were always in support for this traditional variety. Among the other Hasidic sects it is most used by the Satmars.
While Calabria is at the southern point of Italy, and its climate most Mediterranean, it is the most suitable for the citron. Even though, during the winter it is still too cold for the citron, and this is why the farmers need to protect them with blue or green plastic covers. Most of the citron trees in the area are grafted onto foreign rootstock, to save them from freeze and all different kinds of illness. While this practice renders their fruits to non-kosher for the ritual, no citron is to be picked off unless the tree is carefully inspected by a mashgiach.
A Jewish delegation comes from Israel to Santa Maria del Cedro every year between July and August to choose the best fruit to be used in the most important holiday for the Jewish community. The selection of the best fruit is a virtual ritual. The mashgichim, each followed by a peasant carrying a box and a pair of scissors, go to the citron farms at five in the morning. The mashgiach proceeds slowly looking left and right. Then he stops and looks at the base of the tree, right where the trunk comes up from the ground. A smooth trunk means the tree has not been grafted and the fruit can be picked. The mashgiach lies down on the ground to examine better the lower branches between the leaves.
Once the good fruit is found, the mashgiach shows it to the peasant who cuts it off leaving a piece of the stalk. Then the mashgiach analyses the picked citron one more time and if he decides it is worthy he wraps it in oakum and puts it in the box. The farmer receives the agreed sum for each picked fruit. Then the boxes are sealed and sent to the Lamezia Terme airport with a final destination Tel Aviv.
Although Diamante is also growing in Puerto Rico, Sicily and Sardinia, their etrogs are not used for the Jewish ritual, since no kashrut certification was present at tranplantation. Seeds and cuttings of inspected trees were planted in the Israeli village of Kfar Chabad, with the hechsher certification by major kashrut organizations.
The methods for tree checking to verify if the tree is grafted or not, were established by a board of rabbi's in Israel by year 1877 as described in Kuntres Pri Etz Hadar which was published in Jerusalem a year after.