Butbeforecompletingthesale，thecrownjewellersmadeonemoreapplicationtothequeen，declaringthatifshewouldconsenttotakethenecklace，theywouldbecontentwithanyconditionsofpayment。Inthemeantime，theprivatetreasuryofthequeenwasempty。Theseverewinterhadinducedmuchsufferingandmisfortune，andthequeenhadgivenallherfundstothepoor。Butassheearnestlydesiredtopurchasethenecklace，shewouldgivehergrandalmoneraspecialmarkofherfavoringrantingtohimthecommissionofpurchasingitinhername。Heshouldreceiveapaperfromthequeen’sownhandauthorizingthepurchase，yetheshouldkeepthistohimself，andshowitonlytothecourtjewellersatthetimeofthepurchase。Thefirstpaymentofsixhundredthousandfrancsthecardinalwastopayfromhisownpurse，theremainingmillionthequeenwouldpayininstalmentsofonehundredthousandfrancseach，attheexpirationofeverythreemonths。Inthenextthreemonths，thesixhundredthousandfrancsadvancedbythecardinalshouldberefunded。
Thecardinalfelthimselfhighlyflatteredbythistokenofthequeen’sconfidence，anddesirednothingmorethanthewrittenauthorizationofthequeen，empoweringhimtomakethepurchaseatonce。Thisdocumentwasnotwaitedforlong。TwodaysonlypassedbeforetheCountessLamotte-Valoisbroughtit，datedatTrianon，andsubscribedMarieAntoinetteofFrance。Meanwhilesomedoubtsaroseinthemindofthecardinal。Heturnedtohisfriendandadviser，CountCagliostro，forcounsel。Thelatterhadcuredhimyearsbeforewhileverysick，andsincethattimehadalwaysbeenhisdisinterestedfriend，andtheprophet，sotospeak，whoalwaysindicatedthecardinal’sfuturetohim。Thisman，soclearinhisforesight，soskilfulinmedicine，wasnowtakenintoconfidence，andhisadviceasked。CountCagliostrosummonedthespiritsthatwaiteduponhim，beforethecardinal，onesolitarynight。Heaskedtheseinvisiblepresenceswhattheircounselwas，andtheoracleanswered，thattheaffairwasoneworthyofthestationofthecardinal；thatitwouldhaveafortunateissue；thatitputthesealuponthefavorsofthequeen，andwouldusherinthefortunatedaywhichwouldbringthegreattalentsofthecardinalintoemploymentforthebenefitofFranceandtheworld。Thecardinaldoubtedandhesitatednolonger。HewentatoncetothecourtjewellersBohmerandBassenge：hedidnotconcealfromthemthathewasgoingtobuythenecklaceinthenameofthequeen，andshowedthemthewrittenauthorization。Thejewellersenteredreadilyintothetransaction。
Thecardinalmadeadepositofsixhundredthousandfrancs，andBohmerandBassengegavehimthenecklace。Itwasthedaybeforeagreatfestival，andatthefestivalthequeenwantedtowearthenecklace。IntheeveningatrustedservantofthequeenwastotakethenecklacefromthedwellingoftheCountessLamotte-Valois。Thecountessherselfrequestedthecardinaltobepresent，thoughunseen，whenthedeliveryshouldtakeplace。
Inaccordancewiththisagreement，thecardinalrepairedtothepalaceofthecountessontheeveningofFebruary1st，1784，accompaniedbyatrustedvalet，whocarriedthecasketwiththenecklace。Atthedoorwayhehimselftookthecollarandgaveittothecountess。Sheconductedthecardinaltoanalcoveadjoininghersitting-room。Throughthedoorprovidedwithglasswindowshecoulddimlyseethesitting-room。
Aftersomeminutesthemainentranceopened，andavoicecried：“Intheserviceofthequeen!“Amanintheliveryofthequeen，whomthecardinalhadoftenseenatthecountess’s，andwhomshehadtoldwasaconfidentialservantofthequeen，enteredanddemandedthecasketinthenameofthequeen。TheCountessValoistookitandgaveittotheservant，whobowedandtookhisleave。Atthemomentwhenthemandeparted，bearingthiscostlysetofjewels，thecardinalexperiencedaninexpressiblesenseofsatisfactionathavinghadthehappinessofconferringaserviceupontheQueenofFrance，thewifeoftheking，themotherofthefutureking，——notmerelyinthepurchaseofthediamondswhichshedesired，butstillmoreinpreventingtheyoungandimpulsivewomanfromtakingtheunbecomingstepofapplyingtoanyothergentlemanofthecourtforthisassistance。